U.S. patent application number 14/418369 was filed with the patent office on 2015-10-22 for display device with touch panel.
The applicant listed for this patent is Konica Minolta, Inc.. Invention is credited to Hiroshi BEKKU, Satoshi OKANO, Kentaro YANO.
Application Number | 20150301667 14/418369 |
Document ID | / |
Family ID | 50237078 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150301667 |
Kind Code |
A1 |
YANO; Kentaro ; et
al. |
October 22, 2015 |
DISPLAY DEVICE WITH TOUCH PANEL
Abstract
A touch panel (20) is attached, via a reflection-prevention
layer (31) or an adhesive layer, to the polarizing plate (2) side
of a display device (10) having the polarizing plate (2) laminated
upon a display panel (1). The polarizing plate (2) has: a polarizer
(3); and a film (4) having a film thickness of no more than 35
.mu.m and laminated on the touch panel (20) side of the polarizer
(3). The contact angle for the surface of the touch panel (20) side
in the film is less than 60.degree..
Inventors: |
YANO; Kentaro; (Tokyo,
JP) ; BEKKU; Hiroshi; (Tokyo, JP) ; OKANO;
Satoshi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Konica Minolta, Inc. |
Tokyo |
|
JP |
|
|
Family ID: |
50237078 |
Appl. No.: |
14/418369 |
Filed: |
August 29, 2013 |
PCT Filed: |
August 29, 2013 |
PCT NO: |
PCT/JP2013/073143 |
371 Date: |
January 29, 2015 |
Current U.S.
Class: |
345/173 |
Current CPC
Class: |
G06F 3/0445 20190501;
G06F 3/0446 20190501; G06F 3/0412 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2012 |
JP |
2012-195832 |
Claims
1. A display device with a touch panel in which a touch panel is
fitted through an anti-reflection layer or an adhesive agent layer
to a display device, on a side of a polarization plate, where the
polarization plate is stacked in layers on a display panel, wherein
the polarization plate includes a polarizer and a film which is
stacked in layers on the polarizer on a side of the touch panel and
whose film thickness is equal to or less than 35 .mu.m, and a
contact angle on a surface of the film on the side of the touch
panel is less than 60.degree..
2. The display device with a touch panel according to claim 1,
wherein the film thickness of the film is equal to or less than 33
.mu.m, and the contact angle on the film is equal to or less than
55.degree..
3. The display device with a touch panel according to claim 1,
wherein the film thickness of the film is equal to or less than 28
.mu.m, and the contact angle on the film is equal to or less than
55.degree..
4. The display device with a touch panel according to claim 1,
wherein a front layer of the film on the side of the touch panel is
an acrylic resin layer, and the acrylic resin layer is formed with
a coating composition which includes a multifunctional acrylic, a
urethane prepolymer and a reactive silica particle.
5. The display device with a touch panel according to claim 1,
wherein the film includes cellulose.
6. The display device with a touch panel according to claim 1,
wherein the film include: an ester compound having a structure
obtained by reaction of phthalic acid, adipic acid and at least one
type of benzene monocarboxylic acid with at least one type of
alkylene glycol having 2 to 12 carbon atoms; and a cellulose
triacetate having an acetyl group substitution degree of 2.80 to
2.95 and a number average molecular weight equal to or more than
125000 but less than 155000.
7. The display device with a touch panel according to claim 1,
wherein the film is a hard coat film in which a hard coat layer is
stacked in layers on a film base member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a display device with a
touch panel in which the touch panel is fitted on a display panel
through a polarization plate.
BACKGROUND ART
[0002] As in recent years, various types of electronic devices such
as a mobile telephone, a portable terminal device and a personal
computer have become multifunctional and diversified, touch panels
are used as one of the input units for those electronic devices.
The touch panel is optically transparent, and is fitted through an
anti-reflection layer or an adhesive agent to the side of a
polarization plate in a display device where the polarization plate
is stacked in layers on a display panel. As the touch panel
described above, various types such as a capacitive touch panel are
proposed.
[0003] As a typical capacitive touch panel, there is a capacitive
touch panel in which on a transparent substrate, an X electrode
pattern (transparent conductive film) extending in an X direction
is formed, and on this pattern, through an insulating film, a Y
electrode pattern (transparent conductive film) extending in a Y
direction is formed. When the surface of the substrate in the touch
panel is pressed by a finger, since the X electrode pattern and the
Y electrode pattern are brought into contact to vary the
capacitance in its position, the variation in capacitance is
detected through the X electrode pattern and the Y electrode
pattern, with the result that it is possible to identify the
pressed position. This type of capacitive touch panel is disclosed
in, for example, patent document 1.
RELATED ART DOCUMENT
Patent Document
[0004] Patent document 1: Japanese Unexamined Patent Application
Publication No. 2012-8255 (see paragraphs [0106] to [0108], FIGS. 4
and 5 and the like)
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0005] In recent years, the thickness and the weight of the display
device have been reduced, and not only the display panel but also
the polarization plate stacked in layers on the display panel has
been reduced in thickness. Since the thickness of the polarization
plate is reduced as described above to increase the amount of light
transmitted in the display device itself, it is possible to achieve
energy conservation (to reduce power consumption) and to enhance
display brightness.
[0006] However, on the other hand, the thickness of the display
device is reduced, and thus the impact resistance to the pressing
of the touch panel is easily degraded. Specifically, a load when
the touch panel is pressed is easily placed on the junction portion
between the touch panel and the display device (in particular, the
polarization plate), and thus it is impossible to satisfactorily
maintain the adhesion of an anti-reflection layer or an adhesive
agent layer in the junction portion described above. Consequently,
the anti-reflection layer or the adhesive agent is separated from
the display device. Since the separation of the anti-reflection
layer or the adhesive agent described above is more remarkably
found as display unevenness by increasing the amount of light
transmitted in the display device, the visibility of the display
device is lowered.
[0007] A configuration in which the thickness of the polarization
plate is increased to enhance the impact resistance is not
appropriate because this prevents the reduction in the thickness of
the display device and the reduction in the weight thereof and this
also increases, when an endurance test is performed by heating, the
warpage of the polarization plate to easily perform the separation
of the anti-reflection layer or the adhesive agent.
[0008] In view of the foregoing conditions, an object of the
present invention is to provide a display device with a touch panel
in which the thickness of a polarization plate is decreased to
reduce the separation of an anti-reflection layer or an adhesive
agent, and thus it is possible to avoid a decrease in the
visibility of the display device.
Means for Solving the Problem
[0009] The above object of the present invention is achieved by the
following configuration.
[0010] 1. A display device with a touch panel in which a touch
panel is fitted through an anti-reflection layer or an adhesive
agent layer to a display device, on a side of a polarization plate,
where the polarization plate is stacked in layers on a display
panel, where the polarization plate includes a polarizer and a film
which is stacked in layers on the polarizer on a side of the touch
panel and whose film thickness is equal to or less than 35 .mu.m,
and a contact angle on a surface of the film on the side of the
touch panel is less than 60.degree..
[0011] 2. The display device with a touch panel according to the
item 1, where the film thickness of the film is equal to or less
than 33 .mu.m, and the contact angle on the film is equal to or
less than 55.degree..
[0012] 3. The display device with a touch panel according to the
item 1 or 2, where the film thickness of the film is equal to or
less than 28 .mu.m, and the contact angle on the film is equal to
or less than 55.degree..
[0013] 4. The display device with a touch panel according to any
one of the items 1 to 3, where a front layer of the film on the
side of the touch panel is an acrylic resin layer, and the acrylic
resin layer is formed with a coating composition which includes a
multifunctional acrylic, a urethane prepolymer and a reactive
silica particle.
[0014] 5. The display device with a touch panel according to any
one of the items 1 to 4, where the film includes cellulose.
[0015] 6. The display device with a touch panel according to any
one of the items 1 to 5, where the film include: an ester compound
having a structure obtained by reaction of phthalic acid, adipic
acid and at least one type of benzene monocarboxylic acid with at
least one type of alkylene glycol having 2 to 12 carbon atoms; and
a cellulose triacetate having an acetyl group substitution degree
of 2.80 to 2.95 and a number average molecular weight equal to or
more than 125000 but less than 155000.
[0016] 7. The display device with a touch panel according to any
one of the items 1 to 6, where the film is a hard coat film in
which a hard coat layer is stacked in layers on a film base
member.
Advantages of the Invention
[0017] In the configuration described above, the thickness of the
polarization plate is decreased to reduce the separation of the
anti-reflection layer and the adhesive agent, and thus it is
possible to avoid a decrease in the visibility of the display
device.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 A cross-sectional view showing a schematic
configuration of a display device with a touch panel according to
an embodiment of the present invention; and
[0019] FIG. 2 A cross-sectional view showing another configuration
of the display device with the touch panel.
BEST MODE FOR CARRYING OUT THE INVENTION
Display Device with a Touch Panel
[0020] FIG. 1 is a cross-sectional view showing a schematic
configuration of a display device with a touch panel according to
the present embodiment, and FIG. 2 is a cross-sectional view
showing another configuration of the display device with the touch
panel. As shown in these views, in the display device with the
touch panel, on the side of a polarization plate 2 in the display
device 10 where the polarization plate 2 is stacked in layers on a
display panel 1, the touch panel 20 is fitted through an
anti-reflection layer 31 or an adhesive agent layer 32.
[0021] The display panel 1 of the display device 10 can be formed
with a liquid crystal display panel or an organic EL television set
(OLED (organic light-emitting diode)--TV). As the liquid crystal
display panel, the liquid crystal display panels of various drive
methods such as an IPS (in plane switching) method and a TN
(twisted nematic) method can be used.
[0022] The polarization plate 2 is formed with a polarizer 3 that
transmits predetermined linearly polarized light, a film 4 that is
sequentially stacked in layers on the polarizer 3 on the side of
the touch panel 20 and a film 5 that is stacked in layers on the
polarizer 3 on the side of the display device 10. The film 4 is
formed with a hard coat film in which a hard coat layer 4b is
stacked in layers on a film base member 4a. The film 4 may be
formed with the film base member 4a alone (without the hard coat
layer 4b being stacked in layers). The hard coat layer 4b is
provided for protecting the surface of the polarization plate
2.
[0023] A contact angle on the surface (the surface of the hard coat
layer 4b) of the film 4 on the side of the touch panel 20 is set
less than 60.degree.. Such a contact angle can be realized by
appropriately selecting the constituent materials of the film 4 (in
particular, the hard coat layer 4b). The thickness of the film 4
(the total of the thicknesses of the film base member 4a and the
hard coat layer 4b) is equal to or less than 35 .mu.m. The
preferable range of the contact angle is equal to or less than
55.degree., and the preferable range of the thickness of the film 4
is equal to or less than 33 .mu.m and the more preferable range is
equal to or less than 28 .mu.m.
[0024] When the display panel 1 is formed with an OLED, the
polarization plate 2 is formed with a circularly polarizing plate
for preventing the reflection of external light. Such a circularly
polarizing plate is formed by adhering the polarizer 3 and the film
4 such that the optical axis of the polarizer 3 intersects the slow
axis of the film 4 (the film base member 4a) at angle of
45.degree..
[0025] The touch panel 20 is a capacitive touch panel, and is
formed by stacking in layers, on a glass substrate 21, a first
electrode pattern 22 formed with a transparent conductive film, an
interlayer insulating layer 23 and a second electrode pattern 24
formed with a transparent conductive film in this order. The
surface of the glass substrate 21 is the touch surface of the touch
panel 20. An insulting film may be provided so as to further cover
the second electrode pattern 24.
[0026] The first electrode pattern 22 is formed so as to extend on
the glass substrate 21 in one direction (for example, an X
direction). The interlayer insulating layer 23 is formed on the
glass substrate 21 so as to cover the first electrode pattern 22.
The second electrode pattern 24 is formed so as to extend in a
direction (for example, a Y direction) intersecting the direction
in which the first electrode pattern 22 extends. When the surface
of the touch panel 20 is pressed by a finger, the first electrode
pattern 22 and the second electrode pattern 24 touch each other,
and the capacitance between the first electrode pattern 22 and the
second electrode pattern 24 is varied. The variation in capacitance
is detected through the first electrode pattern 22 and the second
electrode pattern 24, and thus it is possible to identify the
pressed position (coordinates).
[0027] The anti-reflection layer 31 is a layer for preventing
reflection off the surface, and is formed with, for example, a low
refractive index layer. When the touch panel 20 is adhered to the
edge portion of the display device 10 with an optical adhesive tape
33, in the parts other than the part of the adhesion, the touch
panel 20 is opposite the anti-reflection layer 31 through an air
gap layer 34.
[0028] The adhesive agent layer 32 is formed with an adhesion layer
such as an OCA (optical clear adhesive tape) or a UV curing resin
(OCR). The adhesive agent layer 32 is formed over the entire
surface of the polarization plate 2 in the display device 10, and
joins the touch panel 20 and the display device 10.
[0029] In a configuration in which the touch panel 20 is not fitted
to the surface of the display device 10 (the polarization plate 2),
the contact angle on the surface of the polarization plate 2 is
often set equal to or more than 60.degree. so that water or the
like is prevented, as much as possible, from being adhered to the
surface of the polarization plate 2.
[0030] However, in the present embodiment, as described above, in
the polarization plate 2, the contact angle on the surface of the
film 4 on the side of the touch panel 20 is set less than
60.degree.. The contact angle on the surface of the film 4 is kept
lowered as described above, and thus the anti-reflection layer 31
and the adhesive agent layer 32 are easily attached to the film 4,
with the result that it is possible to enhance the adhesion
thereof. In this way, it is possible to reduce the separation of
the anti-reflection layer 31 or the adhesive agent layer 32.
Moreover, since the film 4 is such a thin film such that the film
thickness is equal to or less than 35 .mu.m, it is possible to
reduce the warpage of the film 4 after an endurance test by
heating, and it is also possible to reduce the separation of the
anti-reflection layer 31 or the adhesive agent layer 32 caused by
the warpage of the film 4.
[0031] Hence, even when the thickness of the display device 10 is
reduced to increase the amount of light transmitted, it is possible
to reduce display unevenness caused by the separation described
above, and it is possible to avoid a decrease in the visibility of
the display device 10. Since the film 4 is such a thin film that
the film thickness is equal to or less than 35 .mu.m, the thickness
of the polarization plate 2 can be sufficiently reduced, and thus
it is possible to sufficiently contribute to the reduction in the
thickness of the display device 10 and the reduction in the weight
thereof.
[0032] In the configuration of the present embodiment, the
thickness of the polarization plate 2 is reduced, and thus it is
possible to reduce the separation of the anti-reflection layer 31
or the adhesive agent layer 32 and to avoid a decrease in the
visibility of the display device 10. These effects can be reliably
obtained when the contact angle on the film 4 is equal to or less
than 55.degree., and the thickness of the film 4 is equal to or
less than 33 .mu.m (more preferably, is equal to or less than 28
.mu.m).
[0033] Here, the surface layer of the film 4 on the side of the
touch panel 20, that is, the hard coat layer 4b is formed with an
acrylic resin layer, and the acrylic resin layer is preferably
formed with a coating composition that includes a multifunctional
acrylic, a urethane prepolymer and a reactive silica particle.
[0034] The surface layer of the film 4 is formed as described
above, and thus it is possible to reliably realize the film 4 in
which the contact angle on its surface is less than 60.degree.
(more preferably is equal to or less than 55.degree.).
[0035] The film 4 (the film base member 4a) may include cellulose.
More specifically, the film 4 may include: an ester compound having
a structure obtained by reaction of phthalic acid, adipic acid and
at least one type of benzene monocarboxylic acid with at least one
type of alkylene glycol having 2 to 12 carbon atoms; and a
cellulose triacetate having an acetyl group substitution degree of
2.80 to 2.95 and a number average molecular weight equal to or more
than 125000 but less than 155000.
[0036] In the configuration using the film 4 (the film base member
4a) described above, the effects of the present embodiment
described above can be obtained.
[0037] [About the Polarization Plate]
[0038] The individual layers of the polarization plate 2 described
above will be described in detail below.
[0039] [Film Base Member]
[0040] As the film base member 4a and the film 5 of the
polarization plate 2 (hereinafter collectively referred to simply
as a film base member), a thermoplastic resin or a thermosetting
resin can be used.
[0041] (Thermoplastic Resin)
[0042] The thermoplastic resin refers to a resin that is softened
by being heated to its glass transition temperature or melting
point and can be molded into an intended form.
[0043] As the thermoplastic resin that is a common general-purpose
resin, the followings can be used: cellulose ester, polyethylene
(PE), high density polyethylene, medium density polyethylene, low
density polyethylene, polypropylene (PP), polyvinyl chloride (PVC),
polyvinylidene chloride, polystyrene (PS), polyvinyl acetate
(PVAc), Teflon (registered trademark) (polytetrafluoroethylene,
PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin,
acrylic resin (PMMA) and the like.
[0044] In particular, when strength and rigidity are required, the
followings can be used: polyamide (PA), nylon, polyacetal (POM),
polycarbonate (PC), modified polyphenylene ether (m-PPE, modified
PPE, PPO), polybutylene terephthalate (PBT), polyethylene
terephthalate (PET), glass fiber reinforced polyethylene
terephthalate (GF-PET), cycloolefin polymer (COP) and the like.
[0045] Furthermore, when a high heat distortion temperature and a
long-term use property are required, the followings can be used:
polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE),
polysulfone, polyethersulfone, amorphous polyarylate, liquid
crystal polymer, polyether ether ketone, thermoplastic polyimide
(PI), polyamide-imide (PAI) and the like.
[0046] In the present embodiment, in terms of achieving the effects
of the present embodiment, the thermoplastic resin is preferably
selected from the group consisting of cellulose ester resin,
polycarbonate resin, acrylic resin and polyolefin resin.
[0047] The thickness of the resin film base member is preferably
equal to or more than 20 .mu.m, and is more preferably equal to or
more than 30 .mu.m; the sum of the thickness of the resin film base
member and the thickness of the hard coat layer is preferably equal
to or less than 35 .mu.m in terms of the reduction in the
thickness.
[0048] Particularly preferred resins in the present embodiment will
be described in detail below.
[0049] <Cellulose Ester Resin>
[0050] The cellulose ester resin that can be used in the present
embodiment is preferably at least one type selected from the group
consisting of: lower fatty acid esters of cellulose such as
cellulose (di, tri) acetate, cellulose propionate and cellulose
butyrate; mixed fatty acid esters of cellulose such as cellulose
acetate propionate, cellulose acetate butyrate and cellulose
acetate phthalate; cellulose phthalate; and the like.
[0051] Among them, particularly preferable cellulose esters are
cellulose triacetate, cellulose propionate, cellulose butyrate,
cellulose acetate propionate and cellulose acetate butyrate.
[0052] A mixed fatty acid ester such as cellulose acetate
propionate or cellulose acetate butyrate is preferably a cellulose
resin that includes a cellulose ester which has, as a substituent
group, an acyl group having 2 to 4 carbon atoms and which satisfies
formulas (I) and (II) below simultaneously when it is assumed that
the degree of substitution of an acetyl group is X and the degree
of substitution of a propionyl group or a butyryl group is Y.
2.6.ltoreq.X+Y.ltoreq.3.0 Formula (I)
1.0.ltoreq.X.ltoreq.2.5 Formula (II)
[0053] Among them, in particular, cellulose acetate propionate is
preferably used; among them, it is preferable that
1.9.ltoreq.X.ltoreq.2.5 and 0.1.ltoreq.Y.ltoreq.0.9. The part of
the acyl group described above that is not substituted is generally
present as a hydroxyl group. These can be synthesized by known
methods.
[0054] Furthermore, as the cellulose ester used in the present
embodiment, a cellulose ester in which a ratio of weight average
molecular weight Mw/number average molecular weight Mn is 1.5 to
5.5 is preferably used, the ratio is particularly preferably 2.0 to
5.0, the ratio is further particularly preferably 2.5 to 5.0 and
the cellulose ester in which the ratio is further preferably 3.0 to
5.0 is preferably used.
[0055] Preferably, as the lower fatty acid ester of cellulose, a
cellulose triacetate A having an acetyl group substitution degree
of 2.80 to 2.95 and a number average molecular weight (Mn) equal to
or more than 125000 but less than 155000 is contained. As the
cellulose triacetate A, a cellulose triacetate A in which its
weight average molecular weight (Mw) is equal to or more than
265000 but less than 310000 and Mw/Mn is 1.9 to 2.1 is
preferable.
[0056] In terms of enhancing its pencil hardness, a cellulose
triacetate B in which its acetyl group substitution degree is 2.75
to 2.90, its number average molecular weight (Mn) is equal to or
more than 155000 but less than 180000, Mw is equal to or more than
290000 but less than 360000 and Mw/Mn is 1.8 to 2.0 is preferably
used together with the cellulose triacetate A. When the cellulose
triacetate A and the cellulose triacetate B are used together, the
mass ratio preferably falls within a range of the cellulose
triacetate A: the cellulose triacetate B=100:0 to 20:80.
[0057] <Ester Compound>
[0058] A cellulose ester film preferably contains an ester compound
in terms of excellent moisture impermeability. As the ester
compound, an ester compound having a structure obtained by reaction
of phthalic acid, adipic acid and at least one type of benzene
monocarboxylic acid with at least one type of alkylene glycol
having 2 to 12 carbon atoms is preferable.
[0059] As the ingredients of benzene monocarboxylic acid, for
example, there are benzoic acid, para tertiary butyl benzoic acid,
orusotoruiru acid, metatoruiru acid, p-toluic acid, dimethyl
benzoic acid, ethyl benzoate, normal propyl benzoic acid,
aminobenzoic acid and acetoxy benzoic acid; one type or a mixture
of two or more types thereof can be used. Benzoic acid is most
preferable.
[0060] As the ingredients of alkylene glycol having 2 to 12 carbon
atoms, there are ethylene glycol, 1,2-propylene glycol,
1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol,
1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol),
2,2-diethyl-1,3-propanediol (3,3-dimethylol-pentane),
2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol heptane),
3-methyl-1,5-pentanediol 1,6-hexanediol,
2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexane diol,
2-methyl-1,8-octane diol, 1,9-nonan diol, 1,10-decane diol,
1,12-octadecane diol and the like. One type or a mixture of two or
more types of these glycols is used. In particular, 1,2-propylene
glycol is preferable.
[0061] The raw material cellulose of the cellulose ester used in
the present embodiment may be either wood pulp or cotton linter.
Although the wood pulp may be either conifer or broad-leaf tree,
conifer is more preferable. In terms of separation at the time of
film formation, cotton linter is preferably used. The cellulose
esters made of these can be used as a mixture or alone as
necessary.
[0062] For example, cellulose esters having the following ratios as
a ratio of cellulose ester derived from cotton linter:cellulose
ester derived from wood pulp (conifer):cellulose ester derived from
wood pulp (broad-leaf tree) can be used; 100:0:0, 90:10:0, 85:15:0,
50:50:0, 20:80:0, 10:90:0, 0:100:0, 0:0:100, 80:10:10, 85:0:15 and
40:30:30.
[0063] Preferably, in the cellulose ester resin of the present
embodiment, pH when 1 g thereof is put into 20 ml of pure water
(electric conductivity of 0.1 .mu.S/cm or less, pH of 6.8) and is
agitated in an atmosphere of nitrogen at 25.degree. C. for one hour
is 6 to 7, and electric conductivity is 1 to 100 .mu.S/cm.
[0064] [Film Production Method]
[0065] A preferred method of forming the film base member in the
present embodiment will then be described.
[0066] <Method of Manufacturing the Base Material by a Solution
Cast Film Formation Method>
[0067] 1) Dissolution Step
[0068] A dissolution step is a step of forming a dope by
dissolving, in an organic solvent mainly containing a good solvent
for a thermoplastic resin, a thermoplastic resin, a heat-shrinkable
material and another additive in a dissolution kettle while
agitating them. The good solvent refers to an organic solvent that
has satisfactory solubility for a thermoplastic resin in a method
of manufacturing an optical film by a solution cast film formation
method; main effects are produced for dissolution, and a large
amount of organic solvent used therein is referred to as a main
(organic) solvent or a chief (organic) solvent.
[0069] In the dissolution of a thermoplastic resin, various
dissolution methods can be used such as a method which is performed
under normal pressure, a method which is performed at a temperature
equal to or less than the boiling point of the main solvent, a
method which is performed under pressure at a temperature equal to
or more than the boiling point of the main solvent, a method which
is performed by a cooling dissolution method disclosed in Japanese
Unexamined Patent Application Publication No. 9-95544, Japanese
Unexamined Patent Application Publication No. 9-95557 or Japanese
Unexamined Patent Application Publication No. 9-95538 and a method
which is performed under high pressure and which is disclosed in
Japanese Unexamined Patent Application Publication No. 11-21379.
The method which is performed under pressure at a temperature equal
to or more than the boiling point of the main solvent is
preferable.
[0070] A recycled material is also reused. The recycled material
refers to an item produced by crushing a film into small pieces,
and an item produced by cutting off the sides of the film formed at
the time of film formation or an original film whose specifications
are unsatisfactory due to a scratch or the like.
[0071] 2) Cast Step
[0072] A cast step is a step of feeding a solution to a pressure
die through a solution feed pump (for example, a pressurized
metering gear pump) and casting the dope from a pressure die slit
to a cast position on a meal support member such as an endless
metal belt which performs transfer endlessly, for example, a
stainless belt or a rotating metal drum.
[0073] A pressure die is preferable in which the slit shape of the
base part of the die can be adjusted and in which the film
thickness can be easily made uniform. Examples of the pressure die
include a coat hanger die and a T-die, and either of them is
preferably used. The surface of the metal support member is a
mirror surface. In order to increase the speed of the film
formation, two or more pressure dies may be provided on the metal
support member such that the amount of dope is divided to stack
layers. It is also preferable to obtain the film of a multilayer
structure by a co-cast method of casting a plurality of dopes at
the same time.
[0074] 3) Solvent Evaporation Step
[0075] A solvent evaporation step is a step of heating a web (a
doped film formed by casting the dope on a cast support member) on
the cast support member to evaporate a solvent.
[0076] Although in order to evaporate the solvent, there are a
method of blowing air from the side of the web and/or a method of
transferring heat from the back surface of the support member with
a liquid, a method of transferring heat from the front and back
surfaces with radiation heat and the like, the back surface liquid
heat transfer method is preferable because it has a satisfactory
drying efficiency. A method of combing those is also preferably
used. The web on the support member after the cast is preferably
dried on the support member in an atmosphere of 40 to 100.degree.
C. Preferably, in order to maintain the atmosphere of 40 to
100.degree. C., hot air of this temperature is blown to the upper
surface of the web or heating is performed by way of infrared rays
or the like.
[0077] In terms of surface quality, moisture permeability and
separation, it is preferable to separate the web from the support
member within 30 to 120 seconds.
[0078] 4) Separation Step
[0079] A separation step is a step of separating, in a separation
position, the web in which the solvent is evaporated on the metal
support member. The separated web is fed to the subsequent
step.
[0080] The temperature in the separation position on the metal
support member is preferably 10 to 40.degree. C., and is further
preferably 11 to 30.degree. C.
[0081] Preferably, a residual solvent amount at the time of the
separation of the web on the metal support member when the
separation is performed falls within a range of 50 to 120 mass %
depending on the magnitude of the condition of drying, the length
of the metal support member and the like, and the separation is
performed within such a range. However, when the separation is
performed at the point when a larger residual solvent amount is
present, since the web is excessively soft to degrade flatness at
the time of the separation and to easily produce a crease and a
vertical streak by separation tension, the residual solvent amount
at the time of the separation is determined with consideration
given to both economical speed and quality.
[0082] The residual solvent amount of web is defined by formula
below:
residual solvent amount (%)=(mass of web before heating
processing-mass of web after heating processing)/(mass of web after
heating processing).times.100
[0083] The heating processing when the residual solvent amount is
measured refers to heating processing at 115.degree. C. for one
hour.
[0084] The separation tension when the metal support member and the
film are separated from each other is generally 196 to 245 N/m.
When a crease is easily produced at the time of the separation, the
separation is performed preferably with a tension of 190 N/m or
less, further preferably with a tension from the lowest tension
capable of the separation to 166.6 N/m and more preferably with a
tension from the lowest tension to 137.2 N/m; in particular, the
separation is performed preferably with a tension from the lowest
tension to 100 N/m.
[0085] In the present embodiment, the temperature in the separation
position on the metal support member is preferably set at a
temperature of -50 to 40.degree. C., is more preferably set at a
temperature of 10 to 40.degree. C. and is most preferably set at a
temperature of 15 to 30.degree. C.
[0086] 5) Drying and Stretching Step
[0087] A drying and stretching step is a step of drying the web
with a drying device that transports, after the separation, the web
by cyclically passing through a plurality of rolls arranged within
the drying device and/or a tenter stretching device that clips both
ends of the web with a clip to transport it.
[0088] Although a drying unit which blows hot air to both surfaces
of the web is commonly used, a unit which applies microwaves
instead of air can be used. Significantly sudden drying is more
likely to damage the flatness of the finished film. Drying at a
high temperature is preferably performed when the residual solvent
is about 8 mass % or less. The drying is performed at about 40 to
250.degree. C. throughout the step. In particular, the drying is
preferably performed at 40 to 160.degree. C.
[0089] When the tenter stretching device is used, the device is
preferably used that can independently control, on the left and
right, the grasping length (the distance from the start of the
grasping to the completion of the grasping) of the film with the
left/right grasping unit of the tenter. Preferably, in the tenter
step, in order to improve the flatness, partitions having
intentionally different temperatures are also formed.
[0090] In order to prevent the partitions from interfering with
each other, a neutral zone is preferably provided between the
different-temperature partitions.
[0091] The stretching operation may be divided into multiple stages
and performed, and biaxial stretching is preferably performed both
in the direction of cast and in the widthwise direction. When the
biaxial stretching is performed, the biaxial stretching may be
performed simultaneously or may be performed stepwise.
[0092] In this case, the "stepwise" indicates, for example, that it
is possible to sequentially perform the rounds of stretching in
different directions of stretching or that it is possible to divide
stretching in the same direction into multiple stages and add
stretching in a different direction to any one of the stages.
Specifically, for example, the following stretching steps can be
performed.
[0093] a) stretching in the direction of cast--stretching in the
widthwise direction--stretching in the direction of
cast--stretching in the direction of cast b) stretching in the
widthwise direction--stretching in the widthwise
direction--stretching in the direction of cast--stretching in the
direction of cast
[0094] The simultaneous biaxial stretching includes a case where
stretching is performed in one direction, and is performed in the
other direction, while tension is alleviated to perform
contraction. A stretching factor preferable for the simultaneous
biaxial stretching can be set within a range of 1.01 to 1.5 both in
the widthwise direction and in the longitudinal direction.
[0095] The residual solvent amount of web when stretching is
performed is preferably 20 to 100 mass % at the start of the
stretching and drying is preferably performed while the stretching
is performed until the residual solvent amount of web reaches 10
mass % or less, and further preferably reaches 5 mass % or
less.
[0096] The drying temperature when stretching is performed is
preferably 30 to 160.degree. C., is further preferably 50 to
150.degree. C. and is most preferably 70 to 140.degree. C.
[0097] In the stretching step, the temperature differences of the
atmosphere in the widthwise direction are preferably small in terms
of enhancing the uniformity of the film, and the temperature
differences in the widthwise direction in the stretching step
preferably fall within .+-.5.degree. C., more preferably falls
within .+-.2.degree. C. and most preferably falls within
.+-.1.degree. C.
[0098] 6) Winding Step
[0099] A winding step is a step of winding the film with a winding
machine after the residual solvent amount of web reaches 2 mass %
or less, and the residual solvent amount is set at 0.4 mass % or
less and thus it is possible to obtain a film having satisfactory
dimensional stability. In particular, it is preferable to wind it
when the residual solvent amount is 0.00 to 0.10 mass %.
[0100] As the winding method, a commonly used method may be
adopted, and there are a constant torque method, a constant tension
method, a taper tension method, a constant internal stress program
tension control method and the like, and any of them is preferably
used depending on the situation.
[0101] The film base member according to the present embodiment is
preferably a long film. Specifically, a film base member having a
length of about 100 to 5000 m is indicated, and is generally
provided in the form of a roll. The width of the film is preferably
1.3 to 4 m, and is more preferably 1.4 to 2 m.
[0102] <Method of Manufacturing the Base Member by a Melt Cast
Film Formation Method>
[0103] A method of manufacturing the film base material according
to the present embodiment by a melt cast film formation method will
then be described.
[0104] <Step of Manufacturing Melting Pellets>
[0105] Preferably, in general, a composition that is used for melt
extrusion and that includes a resin is previously kneaded into
pellets.
[0106] The pellets may be formed by a known method; for example, an
additive formed of a dried thermoplastic resin, a heat-shrinkable
material and the like is fed by a feeder into an extruder, is
kneaded with a one-axis or two-axis extruder, is extruded from a
die into the form of a strand, is water-cooled or air-cooled and is
cut, with the result that it is possible to form it into
pellets.
[0107] It is important to dry the raw material before extrusion in
terms of preventing the decomposition of the raw material. Since in
particular, a cellulosic ester easily absorbs moisture, it is dried
with a dehumidified hot air dryer or a vacuum dryer at a
temperature of 70 to 140.degree. C. for three hours or more with
the result that its moisture percentage is preferably 200 ppm or
less and is further preferably 100 ppm or less.
[0108] The additives may be mixed before being fed into the
extruder or may be individually fed by the feeder. Preferably, a
small amount of additives such as particles and an antioxidant may
be previously mixed such that they are uniformly mixed.
[0109] With respect to the mixture of the antioxidant, solids may
be mixed with each other, the antioxidant may be mixed, as
necessary, after being dissolved in a solvent and impregnated into
a thermoplastic resin or the antioxidant may be mixed by
spraying.
[0110] In terms of performing drying and mixture simultaneously, a
vacuum Nauta mixer or the like is preferably used. Preferably, when
an exit from a feeder portion or the die and the like are in
contact with air, they are placed in an atmosphere of dehumidified
air, dehumidified N.sub.2 gas or the like.
[0111] Preferably, in the extruder, its shear force is reduced, it
is possible to form a resin into pellets such that the resin is not
degraded (for example, a decrease in molecular weight, coloring or
gel formation) and processing is performed at as low a temperature
as possible. Preferably, for example, in the case of a two-axis
extruder, a deep groove-type screw is used, and rotation in the
same direction is performed. In terms of the uniformity of
kneading, it is preferable to use a meshing type.
[0112] The pellets obtained as described above are used to form the
film. The pellets are not formed, and the powder of the raw
material itself can be fed with the feeder into the extruder and
formed into the film.
[0113] <Step of Extruding a Molten Mixture from the Die to a
Cooling Roll>
[0114] With a one-axis or two-axis extruder, at a melting
temperature Tm of about 200 to 300.degree. C. at the time of the
extrusion, after foreign matters are removed by filtration with a
leaf disc-type filter or the like, the produced pellets are
co-extruded from a T dire into the form of a film, is solidified on
a cooling roll and is cast while being pressed between the cooling
roll and an elastic touch roll. Tm represents a temperature of the
exit portion of the die in the extruder.
[0115] Preferably, at the time of introduction from a feed hopper
into the extruder, under vacuum, under reduced pressure or in an
atmosphere of an inert gas, oxidative decomposition or the like is
prevented.
[0116] When a scratch is produced in the die or a foreign matter
such as a condensate of a plasticizer is attached to the die, a
streaky defect may be produced. Such a defect is also referred to
as a die line; in order to reduce a defect such as a die line on
the surface, it is preferable to adopt a structure in which in
piping from the extruder to the die, the residence portion of the
resin is minimized. It is preferable to use a die in which a
scratch or the like within the die or in a lip is minimized,
[0117] Preferably, on the inner surface of the extruder, the die
and the like in contact with the molten resin, surface processing
for reducing the attachment of the molten resin is performed, for
example, by reducing its surface roughness or by using a material
whose surface energy is low. Specifically, the inner surface that
undergoes hard chrome plating or ceramic thermal spray is ground
such that the surface roughness is 0.2 S or less.
[0118] Although there is no particular restriction on the cooling
roll, a roll having such a structure that it is formed with a
high-rigidity metal roll and a heating medium or a cooling medium
capable of temperature control flows therewithin is preferably
used. Although the size of the cooling roll is not limited, the
cooling roll preferably has a size large enough to cool the film
molten and extruded; in general, the diameter of the cooling roll
is about 100 mm to 1 m.
[0119] Examples of the surface material of the cooling roll include
carbon steel, stainless steel, aluminum and titanium. Furthermore,
in order to increase the hardness of the surface or improve
separation from the resin, surface processing such as hard chrome
plating, nickel plating, amorphous chromium plating or ceramic
thermal spray is preferably performed.
[0120] The surface roughness of the cooling roll is preferably 0.1
.mu.m or less in Ra, and is further preferably 0.05 .mu.m or less.
As the surface of the roll is more smoothed, the surface of the
obtained film can be more smoothed. It is needless to say that
preferably, the surface on which the surface processing is
performed is further ground so as to have the surface roughness
described above.
[0121] As the elastic touch roll, it is possible to use a silicon
rubber roll whose surface is coated with a thin film metal as
disclosed in Japanese Unexamined Patent Application Publication No.
03-124425, Japanese Unexamined Patent Application Publication No.
08-224772, Japanese Unexamined Patent Application Publication No.
07-100960, Japanese Unexamined Patent Application Publication No.
10-272676, WO97/028950, Japanese Unexamined Patent Application
Publication No. 11-235747, Japanese Unexamined Patent Application
Publication No. 2002-36332, Japanese Unexamined Patent Application
Publication No. 2005-172940 and Japanese Unexamined Patent
Application Publication No. 2005-280217.
[0122] When the film is separated from the cooling roll, it is
preferable to prevent deformation of the film by controlling
tension.
[0123] [Method of Manufacturing a Composite Resin Film]
[0124] The film base member of the present embodiment can be formed
with a composite resin film. As a method of manufacturing a
composite resin film, there is a manufacturing method including a
film formation step by a co-cast method and a manufacturing method
including a film formation step by a co-extrusion method.
[0125] <Co-Cast Method: Double Case Method>
[0126] In a metal support member in a cast step, its surface is
preferably mirror-finished; as the metal support member, a
stainless steel belt or a drum whose surface has platted finish by
casting is preferably used. The width of the cast can be set at 1
to 4 m.
[0127] The surface temperature of the metal support member in the
cast step is set within a range from -50.degree. C. to a
temperature at which a solvent is prevented from being boiled to
foam. Although it is preferable to increase the temperature because
the drying speed can be increased, when the temperature is
excessively increased, the web may be foamed or the flatness may be
degraded. A preferred support member temperature is determined as
necessary to fall within a range of 0 to 100.degree. C., and a
range of 5 to 30.degree. C. is more preferable. To cool the web
into gel and separate it from the drum in a state where a large
amount of residual solvent is contained is also a preferred
method.
[0128] Although a method of controlling the temperature of the
metal support member is not particularly limited, there are a
method of spraying hot air or cold air and a method of bringing hot
water into contact with the back side of the metal support member.
Since in the method using hot water, heat is transmitted more
efficiently, and thus it takes less time to make the temperature of
the metal support member constant, the method using hot water is
preferable. As the method using hot air, there is a method of using
hot air whose temperature is equal to or more than the boiling
point of the solvent with consideration given to a decrease in the
temperature of the web caused by the latent heat of vaporization of
the solvent and of using air whose temperature is higher than the
intended temperature while preventing foaming Preferably, in
particular, from the cast until the separation, the temperature of
the support member and the temperature of the dry air are changed,
and drying is efficiently performed.
[0129] Preferably, in the present embodiment, the solution of
acetylated cellulose is divided and thus cast is performed twice or
more times.
[0130] A prepared dope A is cast by the die to the stainless steel
belt, and on the cast web, a prepared dope B is further cast
through the die so as to be stacked in layers. The web stacked in
layers is separated at a separation point, and thereafter is dried
in a dry zone and is wound.
[0131] The compositions of the dope A and the dope B are not
particularly limited, and any composition ratio of an acetylated
cellulose, a cellulose nanofiber, other additives and solvents can
be adopted. The thickness of the cast film of the dope A and the
dope B is not particularly limited. Division cast can also be
performed three or more times.
[0132] In the present embodiment, the cast is divided as described
above, and thus it is possible to easily control the state of the
distribution of the cellulose nanofiber within the film, with the
result that it is possible to control the tear strength of the
film, an elastic modulus and the degree of film dimensional change
according to the requirements thereof.
[0133] Preferably, a dry step can be used in which after the
cellulose fiber is cast, the fiber is easily aligned within the
film surface in the dry step.
[0134] <Co-Extrusion Method>
[0135] In the present embodiment, a multilayer film can be produced
by a co-extrusion method. For example, it is possible to produce a
film having a configuration of a skin layer/a core layer/a skin
layer. For example, a large amount of matt agent is present in the
skin layer or can be put into only the skin layer. Larger amounts
of plasticizer and ultraviolet absorber can be put into the core
layer than into the skin layer or the plasticizer and the
ultraviolet absorber may be put into only the core layer. The types
of plasticizer and ultraviolet absorber can also be changed for
each of the core layer and the skin layer; for example, the
plasticizer and/or the ultraviolet absorber having a low volatility
can be contained in the skin layer, and the plasticizer having an
excellent plasticity or the ultraviolet absorber having an
excellent ultraviolet absorptivity can be added to the core layer.
The glass transition temperatures of the skin layer and the core
layer may be different, and the glass transition temperature of the
core layer is preferably lower than that of the skin layer. Here,
both the glass transition temperatures of the skin and the core are
measured, the average value calculated from their volume fractions
is defined as the glass transition temperature Tg described above
and they can likewise be treated. The viscosity of the molten
material containing the cellulose ester at the time of melt cast
may be different between the skin layer and the core layer. Either
the viscosity of the skin layer>the viscosity of the core layer
or the viscosity of the core layer the viscosity of the skin layer
holds true.
[0136] The co-extrusion method described above is a method of using
a plurality of extruders, heating and melting resins stacked in
layers therefrom, combining the resins, then co-extruding it
through a slit-shaped discharge port of a T die, cooling and
solidifying it with a child roll and forming a cast sheet (in a
non-stretched state). As a method of combining the molten resins
and extruding into the sheet through the T die, there are a feed
block method of combining the molten resins and then widening a
manifold and a multi-manifold method of individually widening the
molten resins with manifolds and then combining them. Either of the
methods may be used.
[0137] Preferably, when the core layer and the skin layer are
cooled and solidified with the child roll, a pressure is applied,
and thus the fiber is easily aligned within the film surface and a
linear expansion coefficient within the film surface can be
lowered.
[0138] [Additive]
[0139] (Antioxidant)
[0140] The film base member preferably includes an antioxidant as
an additive. A preferred antioxidant is a phosphorus-based
antioxidant or a phenolic-based antioxidant; more preferably a
phosphorus-based antioxidant and a phenolic-based antioxidant are
combined at the same time. Antioxidants that can be desirably used
in the present embodiment will be described below.
[0141] <Phenolic-Based Antioxidant>
[0142] In the present embodiment, a phenolic-based antioxidant is
preferably used, and in particular, a hindered phenol compound is
preferably used.
[0143] Specific examples of the hindered phenol compound include
n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate,
n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)-acetate, n-octadecyl
3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl
3,5-di-t-butyl-4-hydroxyphenyl benzoate, n-dodecyl
3,5-di-t-butyl-4-hydroxyphenyl benzoate, neo-dodecyl
3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl .beta.
(3,5-di-t-butyl-4-hydroxyphenyl) propionate, ethyl
.alpha.-(4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl
.alpha.-(4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl
.alpha.-(4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate,
2-(n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate,
2-(n-octylthio) ethyl 3,5-di-t-butyl-4-hydroxy-phenyl acetate,
2-(n-octadecyl thio) ethyl 3,5-di-t-butyl-4-hydroxy-phenyl acetate,
2-(n-octadecyl thio) ethyl 3,5-di-t-butyl-4-hydroxy-benzoate,
2-(2-hydroxyethylthio) ethyl 3,5-di-t-butyl-4-hydroxybenzoate,
diethyl glycol bis-(3,5-di-t-butyl-4-hydroxy-phenyl) propionate,
2-(n-octadecyl thio) ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate, stearamide-N,N-bis-[ethylene
3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate],
n-butylimino-N,N-bis-[ethylene 3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate], 2-(2-stearoyloxy ethyl thio) ethyl
3,5-di-t-butyl-4-hydroxybenzoate, 2-(2-stearoyloxy ethyl thio)
ethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl) heptanoate,
1,2-propylene glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)
propionate], ethylene glycol
bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl
glycol bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate],
ethylene glycol bis-(3,5-di-t-butyl-4-hydroxyphenyl acetate),
glycerol-1-n-octadecanoate-2,3-bis-(3,5-di-t-butyl-4-hydroxyphenyl
acetate),
pentaerythritol-tetrakis-[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)
propionate], 1,1,1-trimethylol
ethane-tris[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate],
sorbitol hexa-[3-(3,5-di-t-butyl 4-hydroxyphenyl) propionate],
2-hydroxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl) propionate,
2-stearoyl-oxy-ethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)
heptanoate, 1,6-n-hexanediol-bis
[(3',5'-di-t-butyl-4-hydroxyphenyl) propionate] and
pentaerythritol-tetrakis(3,5-di-t-butyl-4-hydroxyhydrocinnamate).
For example, the hindered phenol compound of the type described
above is commercially available as product names "Irganox 1076" and
"Irganox 1010" by Ciba Japan Company Ltd.
[0144] <Phosphorus-Based Antioxidant>
[0145] As the phosphorus-based antioxidant, a phosphorus-based
compound such as a phosphite, a phosphonite, a phosphinite or a
tertiary phosphane can be used. As the phosphorus-based compound, a
conventionally known compound can be used. For example,
phosphorus-based compounds are preferable that are disclosed in
Japanese Unexamined Patent Application Publication No. 2002-138188,
paragraphs [0022]-[0027] of Japanese Unexamined Patent Application
Publication No. 2005-344044, paragraphs [0023]-[0039] of Japanese
Unexamined Patent Application Publication No. 2004-182979, Japanese
Unexamined Patent Application Publication No. 10-306175, Japanese
Unexamined Patent Application Publication No. 1-254744, Japanese
Unexamined Patent Application Publication No. 2-270892, Japanese
Unexamined Patent Application Publication No. 5-202078, Japanese
Unexamined Patent Application Publication No. 5-178870, Japanese
Unexamined Patent Application Publication (Translation of PCT
Application) No. 2004-504435, Japanese Unexamined Patent
Application Publication (Translation of PCT Application) No.
2004-530759 and Japanese Unexamined Patent Application Publication
No. 2005-353229.
[0146] The amount of phosphorus-based compound added is generally
0.01 to 10 parts by mass with respect to 100 parts by mass of the
resin, is preferably 0.05 to 5 parts by mass and is further
preferably 0.1 to 3 parts by mass.
[0147] In addition to the compounds represented by the above
general formulas, as the phosphorus-based compound, there are: for
example, mono phosphite compounds such as triphenyl phosphite,
diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris
(nonyl phenyl)phosphite, tris (dinonylphenyl)phosphite, tris
(2,4-di-t-butyl-phenyl)phosphite,
10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phospha-phenant-
hrene-10-oxide, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)
propoxy]-2,4,8,10-tetra-t-butyldibenz[d,f][1.3.2]dioxaphosphepin
and tridecyl phosphite; diphosphite-based compounds such as
4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite)
and 4,4'-isopropylidene-bis(phenyl-di-alkyl (C12 to C15)
phosphite); phosphonite compounds such as triphenyl phosphonite,
tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl]-4,4'-diyl bis
phosphonite, tetrakis (2,4-di-tert-butyl-5-methyl phenyl)
[1,1-biphenyl]-4,4'-diylbisphosphonite; phosphinite-based compounds
such as triphenylphosphinite and 2,6-dimethyl-phenyl
diphenylphosphinite; and phosphine compounds such as triphenyl
phosphine and tris (2,6-dimethoxyphenyl)phosphine.
[0148] The phosphorus-based compound of the above type is
commercially available, for example, as product names "Sumilizer
GP" by Sumitomo Chemical Company, Ltd., "ADK STAB PEP-24G", "ADK
STAB PEP-36" and "ADK STAB 3010" by ADEKA Corporation, "IRGAFOS
P-EPQ" by Ciba Japan Company Ltd. and "GSY-P101" by Sakai Chemical
Industry Co., Ltd.
[0149] (Other Antioxidants)
[0150] Other examples of antioxidants include: sulfur-based
antioxidants such as dilauryl-3,3'-thiodipropionate,
dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate
and pentaerythrityltetrakis (3-laurylthiopropionate); heat
processing stabilizers such as 2-tert-butyl-6-(3-tert-butyl-2
hydroxy-5-methylbenzyl)-4-methylphenylacrylate,
2-[1-(2-hydroxy-3,5-di-tert-pentylpheyl)ethyl]-4,6-di-tert-pentylphenylac-
rylate; a 3,4-dihydro-2H-1-benzopyrane type compound; a
3,3'-spirodicumarone type compound, a 1,1-spiroindane type
compound, and a compound provided with a morpholine, thiomorpholine
oxide, thiomorpholine dioxide or piperazine skeleton as a partial
structure which are described in Examined Japanese Patent
Application Publication No. 8-27508; and an oxygen scavenger such
as a dialkoxybenzene type compound described in Japanese Unexamined
Patent Application Publication No. 3-174150. Partial structures of
these antioxidants may be pendent to part of a polymer or regularly
pendent to a polymer or may be introduced into part of the
molecular structure of an additive such as a plasticizer, an acid
scavenger or an ultraviolet absorber.
[0151] (Other Additives)
[0152] The film base member according to the present embodiment can
contain, as additives, not only the above compounds and the like
but also various compounds and the like according to the
purpose.
[0153] <Acid Scavenger>
[0154] With respect to an acid scavenger, an epoxy compound as an
acid scavenger described in U.S. Pat. No. 4,137,201 is preferably
incorporated. Such an epoxy compound as an acid scavenger is well
known in the art and includes diglycidyl ether of various
polyglycols, particularly, polyglycol which is derived by
condensation of approximately 8-40 mol of ethyleneoxide per 1 mol
of polyglycol and diglycidyl ether of glycelol; a metal epoxy
compound (for example, those conventionally utilized in and
utilized together with, a vinyl chloride polymer composition); an
epoxidated ether condensate, diglycidyl ether of bisphenol A (that
is 4,4'-dihydroxydiphenylmethyl methane), epoxidated unsaturated
fatty acid ester (particularly, ester of alkyl having a carbon
number of 4-2 and fatty acid having a carbon number of 2-22 (such
as butylepoxy stearate)); and various epoxidated long chain fatty
acid triglycerides (for example, epoxidated vegetable oil and other
unsaturated natural oil represented and exemplified by a
composition of such as epoxidated soy bean oil (these sometimes
referred to as epoxidated natural glyceride or unsaturated fatty
acid, and these fatty acids generally have a carbon number of
12-22)).
[0155] <Light Stabilizer>
[0156] As a light stabilizer, there are hindered amine light
stabilizer (HALS) compounds, and these are known compounds;
examples thereof include 2,2,6,6-tetraalkyl piperidine compounds,
their acid addition salts and complexes of metal compounds
therewith as disclosed in the fifth to eleventh columns of the
specification of U.S. Pat. No. 4,619,956 and the third to fifth
columns of the specification of U.S. Pat. No. 4,839,405.
Furthermore, a light stabilizer disclosed in Japanese Unexamined
Patent Application Publication No. 2007-63311 can be used.
[0157] <Ultraviolet Absorber>
[0158] As the ultraviolet absorber, an ultraviolet absorber is
preferable that has an excellent absorption capacity of ultraviolet
light having wavelengths of 370 nm and less in terms of the
prevention of degradation by ultraviolet light and that little
absorbs visible light having wavelengths of 400 nm and more in
terms of liquid crystal display. Examples thereof include an
oxybenzophenone-based compound, a benzotriazole-based compound, a
salicylate-based compound, a benzophenone-based compound, a
cyanoacrylate-based compound and a nickel complex salt-based
compound; a benzophenone-based compound and a benzotriazole-based
compound having little coloring are preferable. Ultraviolet
absorbers disclosed in Japanese Unexamined Patent Application
Publication No. 10-182621 and Japanese Unexamined Patent
Application Publication No. 8-337574 and a polymer ultraviolet
absorber disclosed in Japanese Unexamined Patent Application
Publication No. 6-148430 may be used.
[0159] Specific examples of the benzotriazole-based compound
include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole,
2-(2'-hydroxy-3',5'-di-tert-butyl phenyl)benzotriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)benzotriazole,
2-(2'-hydroxy-3',5'-di-tert-butyl-phenyl)-5-chloro-benzotriazole,
2-(2'-hydroxy-3'-(3'',4'',5'',6''-tetrahydrophthalimide-methyl)-5'-methyl-
phenyl)benzotriazole, 2,2-methylenebis(4-(1,1,3,3-tetramethyl
butyl)-6-(2H-benzotriazol-2-yl) phenol),
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chloro-benzotriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-(2-octyloxy-carbonyl-ethyl)-phenyl)-5-chlo-
ro-benzotriazole,
2-(2'-hydroxy-3'-(1-methyl-1-phenylethyl)-5'-(1,1,3,3-tetramethyl
butyl)-phenyl)benzotriazole, 2-(2H-benzotriazol-2-yl)-6-(linear and
side chain dodecyl)-4-methylphenol, and a mixture of
octyl-3-[3-tert-butyl-4-hydroxy-5-(chloro-2H-benzotriazol-2-yl)phenyl]pro-
pionate and
2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)p-
henyl]propionate. However, there is no restriction on these.
[0160] Examples of commercially available products include TINUVIN
326, TINUVIN 109, TINUVIN 171, TINUVIN 900, TINUVIN 928 and TINUVIN
360 (all of which are made by Ciba Japan Company Ltd.), LA31 (made
by ADEKA Corporation), Sumisorb 250 (made by Sumitomo Chemical
Company, Ltd.) and RUVA-100 (made by Otsuka Chemical Co.,
Ltd.).
[0161] Specific examples of the benzophenone-based compound
include: 2,4-dihydroxy benzophenone, 2,2'-dihydroxy-4-methoxy
benzophenone, 2-hydroxy-4-methoxy-5-sulfo benzophenone and
bis(2-methoxy-4-hydroxy-5-benzoyl phenyl methane). However, there
is no restriction on these.
[0162] In the present embodiment, 0.1 to 20% by mass of ultraviolet
absorber is preferably added, 0.5 to 10% by mass of ultraviolet
absorber is further preferably added and 1 to 5% by mass of
ultraviolet absorber is further preferably added. Two or more types
thereof may be used together.
[0163] <Matt Agent>
[0164] Minute particles such as a matt agent can be added to the
film base member of the present embodiment; as the minute
particles, there are particles of an inorganic compound and
particles of an organic compound. Examples of the minute particles
include inorganic minute particles of silicon dioxide, titanium
dioxide, aluminum oxide, zirconium oxide, calcium carbonate,
kaolin, talc, burned calcium silicate, hydrated calcium silicate,
aluminum silicate, magnesium silicate and calcium phosphate and
crosslinked polymer particles. Among them, silicon dioxide is
preferable because the haze of the resin substrate can be reduced.
Minute particles of silicon dioxide or the like are often subjected
to surface processing with an organic substance; these minute
particles are preferable because the haze of the resin substrate
can be reduced.
[0165] Examples of the preferred organic substance for the surface
processing include halosilanes, alkoxysilanes, silazane and
siloxane. As the average particle diameter of the minute particles
is increased, the slip effect is increased whereas as the average
particle diameter is reduced, the transparency becomes more
excellent.
[0166] The average particle diameter of the secondary particles of
the minute particles falls within a range of 0.05 to 1.0 .mu.m. The
average particle diameter of the secondary particles of the minute
particles preferably falls within a range of 5 to 50 nm, and
further preferably falls within a range of 7 to 14 nm. These minute
particles are preferably used because in the surface of the
cellulose ester film, projections and recesses of 0.01 to 1.0 .mu.m
are produced in the surface of the cellulose ester film. The
content of the minute particles in the cellulose ester film is
preferably 0.005 to 0.3% by mass with respect to the cellulose
ester.
[0167] Examples of the minute particles of silicon dioxide include
AEROSILs 200, 200V, 300, R972, R972V, R974, 8202, R812, OX50 and
TT600 made by Nippon Aerosil Co., Ltd.; AEROSILs 200V, R972, R972V,
R974, R202 and R812 are preferable. Two or more types of these
minute particles may be used together. When two or more types are
used together, they can be mixed in an arbitrary ratio and be used.
In this case, minute particles having different average particle
diameters and materials, for example, AEROSILs 200V and R972V can
be used in a mass ratio range of 0.1:99.9 to 99.9:0.1.
[0168] The presence of the minute particles in the base material
used as the matt agent described above can also be used as another
purpose for enhancing the strength of the base material.
[0169] [Hard Coat Layer]
[0170] The details of the hard coat layer in the polarization plate
will then be described. In the present embodiment, the hard coat
layer is preferably formed with, for example, an active energy ray
curable resin.
[0171] (Active Energy Ray Curable Resin)
[0172] The active energy ray curable resin is a resin that is cured
after a cross-linking reaction or the like by the application of
active rays such as ultraviolet rays or electron rays;
specifically, the active energy ray curable resin is a resin that
has an ethylenically unsaturated group. More specifically, an
ultraviolet-curable urethane acrylate-based resin, an
ultraviolet-curable polyester acrylate-based resin, an
ultraviolet-curable epoxy acrylate-based resin, an
ultraviolet-curable polyol acrylate-based resin and an ultraviolet
curable epoxy resin are preferably used. Among them, the
ultraviolet-curable acrylate-based resin is preferable.
[0173] As the ultraviolet-curable acrylate-based resin, a
multifunctional acrylate is preferable. The multifunctional
acrylate is preferably selected from the group consisting of a
pentaerythritol multifunctional acrylate, a dipentaerythritol
multifunctional acrylate, a pentaerythritol multifunctional
methacrylate and a dipentaerythritol multifunctional methacrylate.
Here, the multifunctional acrylate is a compound that includes two
or more acryloyl oxy groups or methacryloyl oxy groups in the
molecule.
[0174] Examples of the monomer of the multifunctional acrylate
preferably include ethylene glycol diacrylate, diethylene glycol
diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate,
trimethylol propane triacrylate, trimethylol ethane triacrylate,
tetramethylolmethane triacrylate, tetramethylolmethane
tetraacrylate, pentaglycerol triacrylate, pentaerythritol
diacrylate, pentaerythritol triacrylate, pentaerythritol
tetraacrylate, glycerol triacrylate, dipentaerythritol triacrylate,
dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate,
dipentaerythritol hexaacrylate, tris (acryloyloxyethyl)
isocyanurate, ethylene glycol dimethacrylate, diethylene glycol
dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol
dimethacrylate, trimethylol propane trimethacrylate, trimethylol
ethane trimethacrylate, tetramethylolmethane trimethacrylate,
tetramethylolmethane tetramethacrylate, penta glycerol
trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol
trimethacrylate, pentaerythritol tetramethacrylate, glycerine
trimethacrylate, dipentaerythritol trimethacrylate,
dipentaerythritol tetramethacrylate, dipentaerythritol
pentamethacrylate, dipentaerythritol hexamethacrylate and active
energy ray curable isocyanurate derivatives. As these
multifunctional acrylates, commercially available products may be
used; pentaerythritol tri/tetra acrylate (such as A-TMM-3L, made by
Shin Nakamura Chemical Co., Ltd.), pentaerythritol triacrylate
(PE-3A, made by kyoeisha Chemical Co., Ltd.) and the like are
available. These compounds are used either singly or by mixing two
or more types.
[0175] As the isocyanurate derivative of the active energy ray
curable resin, a compound that has a structure where one or more
ethylenically unsaturated groups are coupled to an isocyanuric acid
skeleton is preferable; there is no particular restriction but a
compound having three or more ethylenically unsaturated groups and
one or more isocyanurate rings is preferable.
[0176] As the isocyanuric acid triacrylate compound described
above, a commercially available product can also be used; examples
thereof include A-9300 made by Shin Nakamura Chemical Co., Ltd.
Examples of the commercially available product of the isocyanuric
acid diacrylate compound include Aronix M-215 made by Toagosei Co.,
Ltd. Examples of the mixture of the isocyanuric acid triacrylate
compound and the isocyanuric acid diacrylate compound include
Aronix M-315, Aronix M-313 and the like made by Toagosei Co., Ltd.
Examples of .epsilon.-caprolactone-modified active energy ray
curable isocyanurate derivative include A-9300-1CL, which is
.epsilon.-caprolactone-modified tris-(acryloxyethyl) isocyanurate
made by Shin Nakamura Chemical Co., Ltd. and Aronix M-327 made by
Toagosei Co., Ltd. but there is no restriction on these.
[0177] As the active energy ray curable resin, a monofunctional
acrylate may be used. Examples of the monofunctional acrylate
include isobornyl acrylate, 2-hydroxy-3-phenoxy-propyl acrylate,
isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate,
phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate,
tetrahydrofurfuryl acrylate, behenyl acrylate, 4-hydroxybutyl
acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and
cyclohexyl acrylate. Monofunctional acrylates are available such as
from Shin Nakamura Chemical Co., Ltd. and Osaka Organic Chemical
Industry Ltd. These compounds are used either singly or by mixing
two or more types. They may be oligomers such as the dimers,
trimers and the like of the monomer described above.
[0178] Furthermore, as the active energy ray curable resin,
urethane acrylate may be used. As the urethane acrylate, for
example, commercially available products can be used such as Beam
set 575CB made by Arakawa Chemical Industries, Ltd. and UA-306H
made by kyoeisha Chemical Co., Ltd.
[0179] The viscosity of the multifunctional acrylate as described
above at 25.degree. C. is preferably 3000 mPas or less, and is
further preferably 1500 mPas or less. It is particularly preferably
1000 mPas or less. Examples of the low-viscosity resin described
above include glycerin triacrylate, pentaerythritol triacrylate and
pentaerythritol tetraacrylate. The viscosity mentioned above is a
value that is measured under conditions of 25.degree. C. with an
E-type viscometer.
[0180] The amount of active energy ray curable resin contained in
the composition of the hard coat layer is, when the entire
composition is assumed to be 100 parts by mass, generally 10 to 99
parts by mass and is preferably 35 to 99 parts by mass. When a
small amount of active energy ray curable resin is contained, it is
difficult to sufficiently obtain the film strength of the hard coat
layer. When a large amount thereof is contained, it is undesirable
because a failure occurs in the uniformity of the film thickness or
as a coating streak when coating is performed by a known coating
method, which will be described later.
[0181] (Cation Polymerizable Compound)
[0182] The hard coat layer may further contain a cation
polymerizable compound. The cation polymerizable compound is a
compound that undergoes cation polymerization by the application of
energy active rays and heat so as to resinify. Specific examples
thereof include an epoxy group, a cyclic ether group, a cyclic
acetal group, a cyclic lactone group, a cyclic thioether group, a
spiroorthoester compound and a viny oxo group. Among them, a
compound having a functional group such as an epoxy group or a
vinyl ether group is preferably used in the present embodiment.
[0183] Examples of the cation polymerizable compound having an
epoxy group or a vinyl ether group include phenyl glycidyl ether,
ethylene glycol diglycidyl ether, glycerol diglycidyl ether, vinyl
cyclohexene dioxide, limonene dioxide,
3,4-epoxycyclohexylmethyl-3',4'-epoxy cyclohexane carboxylate,
bis-(6-methyl-3,4-epoxy cyclohexyl) adipate, 2-(3,4-epoxy
cyclohexyl) ethyl trimethoxy silane, diethylene glycol divinyl
ether, polyethylene glycol divinyl ether and 1,4-cyclohexane
dimethanol divinyl ether. As the epoxy compound, a polymer compound
can also be used.
[0184] When the cation polymerizable compound described above is
included in the hard coat layer composition, and the entire
composition is assumed to be 100 parts by mass, the amount of
cation polymerizable compound contained in the hard coat layer
composition is generally 1 to 90 parts by mass and is preferably 1
to 50 parts by mass.
[0185] (Minute Particles)
[0186] The hard coat layer may contain minute particles. As the
minute particles, there are inorganic minute particles and organic
minute particles. Examples of the inorganic minute particles
include silica, titanium oxide, aluminum oxide, tin oxide, indium
oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium
carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined
calcium silicate, hydrated calcium silicate, silicic acid aluminum,
magnesium silicate and calcium phosphate. Examples of the organic
minute particles include polymethacrylic acid methyl acrylate resin
powder, acrylic styrene-based resin powder, polymethyl methacrylate
resin powder, silicone-based resin powder, polystyrene-based resin
powder, polycarbonate resin powder, benzoguanamine-based resin
powder, melamine-based resin powder, polyolefin-based resin powder,
polyester-based resin powder, polyamide-based resin powder,
polyimide-based resin powder and polyfluorinated ethylene-based
resin powder. The average particle diameter of these minute
particles is preferably 30 to 200 nm in terms of the stability and
the clarity of the hard coat layer coating composition. Two or more
types of minute particles having different particle diameters may
be contained in the hard coat layer. Since the desired pencil
hardness is easily achieved, silica minute particles may be
contained in the hard coat layer.
[0187] In terms of more satisfactorily achieving the action effects
of the present embodiment, reactive silica particles (Xa) whose
surface is processed by an organic compound having a polymerizable
unsaturated group are preferably contained in the hard coat layer.
The reactive silica particles (Xa) whose surface is processed by an
organic compound having a polymerizable unsaturated group will be
described below.
[0188] <<Reactive Silica Particles (Xa)>>
[0189] As the silica particles, known silica particles can be used.
The shape thereof may be spherical or indefinite, and they are not
limited to general colloidal silica and may be hollow particles,
porous particles, core/shell type particles or the like; however,
colloidal silica having a pH of 2.0 to 6.5 is preferable.
[0190] The dispersion medium of the silica particles is preferably
water or an organic solvent. Examples of the organic solvent
include: alcohols such as methanol, isopropyl alcohol, ethylene
glycol, butanol and ethylene glycol mono propyl ether; ketones such
as methyl ethyl ketone and methyl isobutyl ketone; aromatic
hydrocarbons such as toluene and xylene; amides such as
dimethylformamide, dimethylacetamide and N-methylpyrrolidone;
esters such as ethyl acetate, butyl acetate and
.gamma.-butyrolactone; and ethers such as tetrahydrofuran and
1,4-dioxane. Among them, alcohols and ketones are preferable. These
organic solvents can be used as the dispersion medium either singly
or by mixing two or more types. Examples of the commercially
available products of colloidal silica include MEK-ST-L, MEK-ST-MS,
IPA-ST-L, IPA-ST-ZL and the like made by Nissan Chemical
Industries, Ltd.
[0191] The reactive silica particles (Xa) can be obtained by
processing the surface of the colloidal silica as described above
with an organic compound (hereinafter referred to as an "organic
compound (X)") having a polymerizable unsaturated group. The
organic compound (X) is preferably a compound that includes a
polymerizable unsaturated group and preferably an ethylenically
unsaturated group and that further includes a group represented by
general formula (a) below and a silanol group within the molecule
or that generates a silanol group by hydrolysis.
##STR00001##
[0192] Specific six examples of [--U--C(.dbd.V)--NH--] are
[--O--C(.dbd.O)--NH--], [--O--C(.dbd.S)--NH--],
[--S--C(.dbd.O)--NH--], [--NH--C(.dbd.O)--NH--],
[--NH--C(.dbd.S)--NH--] and [--S--C(.dbd.S)--NH--]. These groups
can be used either singly or by combining two or more types. Among
them, in terms of thermal stability, the [--O--C(.dbd.O)--NH--]
group is preferably used together with at least one of the
[--O--C(.dbd.S)--NH--] group and the [--S--C(.dbd.O)--NH--]
group.
[0193] Although the ethylenically unsaturated group included in the
organic compound (X) is not particularly limited, preferred
examples thereof include an acryloyl group, a methacryloyl group
and a vinyl group. This ethylenically unsaturated group is a
constituent unit that undergoes addition polymerization with an
active radical species.
[0194] Examples of the compound that generates a silanol group
include compounds in which an alkoxy group, an aryloxy group, an
acetoxy group, an amino group, a halogen atom and the like are
bonded to a silicon atom; however, a compound in which an alkoxy
group or an aryloxy group is bonded to a silicon atom, that is,
alkoxysilyl group-containing compound or an aryloxysilyl
group-containing compound is preferable. Specific examples thereof
include a compound expressed by general formula (b) below.
##STR00002##
[0195] In general formula (b), R.sup.21 and R.sup.22 may be the
same as or different from each other, and are an alkyl group or an
aryl group having 1 to 8 hydrogen atoms or carbon atoms and
examples thereof include a methyl group, an ethyl group, a propyl
group, a butyl group, an octyl group, a phenyl group and a xylyl
group. Here, j is an integer of 1 to 3.
[0196] Examples of the group represented by
[(R.sup.21O).sub.jR.sup.22.sub.3-jSi--] include a trimethoxysilyl
group, a triethoxysilyl group, a triphenoxysilyl group, a
methyldimethoxysilyl group and a dimethylmethoxysilyl group. Among
these groups, a trimethoxysilyl group, a triethoxysilyl group or
the like are preferable.
[0197] R.sup.23 is a divalent organic group that has an aliphatic
or aromatic structure having 1 to 12 carbon atoms, and may include
a chain-shaped, a branched or a cyclic structure. Specific examples
thereof include methylene, ethylene, propylene, butylene,
hexamethylene, cyclohexylene, phenylene, xylylene and
dodecamethylene.
[0198] R.sup.24 is a divalent organic group that is generally
selected from divalent organic groups having a molecular weight of
14 to 10000, and that is preferably selected from divalent organic
groups having a molecular weight of 76 to 500. Specific examples
thereof include: chain polyalkylene groups such as hexamethylene,
octamethylene and dodecamethylene; an alicyclic or polycyclic
divalent organic groups such as cyclohexylene and norbornylene;
divalent aromatic groups such as phenylene, naphthylene,
biphenylene and polyphenylene; and alkyl group substitutes and aryl
group substitutes thereof. These divalent organic groups may
include an atomic group that includes elements other than carbon
and hydrogen atoms, and can include a polyether bond, a polyester
bond, a polyamide bond and a polycarbonate bond.
[0199] R.sup.25 is a (k+1) valent organic group, and is preferably
selected from chain-shaped, branched or cyclic saturated
hydrocarbon group and unsaturated hydrocarbon group.
[0200] Z represents a monovalent organic group that has, in the
molecule, a polymerizable unsaturated group which undergoes an
intermolecular cross-linking reaction under the presence of an
active radical species. Here, k is preferably an integer of 1 to
20, is further preferably an integer of 1 to 10 and is particularly
preferably an integer of 1 to 5.
[0201] The organic compound (X) can be obtained by directly
subjecting, to an addition reaction, hydrolyzable silane, one or
more compounds that are selected from a polyisocyanate compound, a
poly thioisocyanate compound and a compound having both an
isocyanate group and a chioisoshiane group and an active
hydrogen-containing polymerizable unsaturated compound having an
active hydrogen atom which undergoes addition reaction with an
isocyanate group or a chioisoshiane group.
[0202] Preferably, mercaptopropyl trimethoxysilane and isophorone
diisocyanate are mixed under the presence of dibutyltin dilaurate,
are made to react with each other at a temperature of 60 to
70.degree. C. for about a few hours, thereafter pentaerythritol
triacrylate is added and furthermore, they are made to react with
each other at a temperature of 60 to 70.degree. C. for about a few
hours.
[0203] Then, the obtained organic compound (X) is mixed with the
silica particles, they are made to undergo hydrolysis and both of
them are bonded to each other, with the result that it is possible
to manufacture the reactive silica particles (Xa).
[0204] The amount of organic compound (X) bonded to the silica
particles is, when the silica particles are assumed to be 100% by
mass, preferably 0.01% or more by mass, is further preferably 0.1%
or more by mass and is particularly preferably 1% or more by
mass.
[0205] When the amount falls within the above range, the reactive
silica particles (Xa) in the composition are satisfactorily
dispersed. The proportion of the silica particles in the raw
material when the reactive silica particles (Xa) are manufactured
is preferably 5 to 99% by mass and is further preferably 10 to 98%
by mass. The amount of reactive silica particles (Xa) contained in
the hard coat layer coating composition is, when the total amount
of solid in the composition is assumed to be 100% by mass,
preferably 5 to 80% by mass and is more preferably 10 to 80% by
mass. The reactive silica particles (Xa) are used within the above
range, and thus the reactive silica particles (Xa) in the hard coat
layer coating composition are stably present.
[0206] Preferably, the hard coat layer contains the active energy
ray curable resin and the minute particles described above, and the
content mass ratio thereof is active energy ray curable
resin:minute particles=90:10 to 20:80.
[0207] (Other Additives and Method of Manufacturing the Hard Coat
Layer)
[0208] Preferably, in order to facilitate the curing of the active
energy ray curable resin, a photopolymerization initiator is
further contained in the hard coat layer. Preferably, as the amount
of photopolymerization initiator contained, its mass ratio is
photopolymerization initiator:active energy ray curable
resin=20:100 to 0.01 to 100.
[0209] Specific examples of the photopolymerization initiator
include alkylphenones, acetophenone, benzophenone, hydroxy
benzophenone, Michler's ketone, .alpha.-amyloxime ester,
thioxanthone and the derivatives thereof. However, the
photopolymerization initiator is not limited to these. Commercially
available products may be used as them; preferred examples thereof
include Irgacure 184, Irgacure 907, Irgacure 651 and the like made
by BASF Japan Ltd.
[0210] The hard coat layer may contain the same ultraviolet
absorber as described above.
[0211] Furthermore, preferably, the hard coat layer is formed with
two or more layers, and the hard coat layer in contact with the
film base member contains the ultraviolet absorber in terms of
satisfactorily achieving the object effects of the present
embodiment and satisfactorily obtaining the film strength (scratch
resistance) and the pencil hardness of the hard coat layer.
Preferably, as the amount of ultraviolet absorber contained, its
mass ratio is ultraviolet absorber:hard coat layer
composition=0.01:100 to 10 to 100.
[0212] When two or more hard coat layers are provided, the film
thickness of the hard coat layer in contact with the film base
member preferably falls within a range of 0.05 to 2 .mu.m. Two or
more layers may be simultaneously stacked. The simultaneous
stacking is to coat the surface of the substrate wet on wet without
undergoing the dry step with two or more hard coat layers, and thus
the hard coat layers are formed. The second hard coat layer is
preferably stacked in layers on the first hard coat layer wet on
wet without undergoing the dry step either by stacking the layers
one by one with an extrusion coater or by simultaneously stacking
the layers with a slot die having a plurality of slits.
[0213] As a method of producing the hard coat layer, a method of
applying, drying and curing, by the following method, a hard coat
layer coating composition diluted with a solvent that swells or
partially dissolves a cellulose acetate film, on the cellulose
acetate film, and thereby proving the hard coat layer coating
composition is preferable in terms of easily obtaining interlayer
intimate contact between the hard coat layer and the cellulose
acetate film.
[0214] As the solvent that swells or partially dissolves the
cellulose acetate film, a solvent that includes ketone and/or
acetic acid ester is preferable. Specific examples of ketone
include methyl ethyl ketone, acetone and cyclohexanone. Specific
examples of acetic acid ester include ethyl acetate, methyl acetate
and butyl acetate. The hard coat layer coating composition may
include an alcohol-based solvent as another solvent.
[0215] The amount of hard coat layer coating composition applied is
preferably 0.1 to 40 .mu.m as the wet film thickness, and is
further preferably 0.5 to 30 .mu.m. Although the average film
thickness is about 5 to 20 .mu.m as the dry film thickness, and is
preferably 7 to 12 .mu.m, in the present embodiment, the amount of
hard coat layer coating composition applied is preferably set such
that the total film thickness of the film base member and the hard
coat layer is 35 .mu.m or less.
[0216] It is possible to form the hard coat layer by applying the
hard coat coating composition forming the hard coat layer with a
known application method such as a gravure coater, a dip coater, a
reverse coater, a wire bar coater, a die (extrusion) coater or an
inkjet method, drying after the application, applying active rays
(which is also called UV curing processing) and further performing
heating processing as necessary after the UV curing. The heating
processing temperature after the UV curing is preferably 80.degree.
C. or more, is further preferably 100.degree. C. or more and is
particularly preferably 120.degree. C. or more. The heating
processing is performed at such a high temperature after the UV
curing, and thus the mechanical strength (abrasion resistance and
pencil hardness) of the hard coat layer is more satisfactory.
[0217] The drying is preferably performed by setting a temperature
in a ratio reduction drying period at a high temperature equal to
or more than 80.degree. C. The drying is further preferably
performed by setting the temperature in the ratio reduction drying
period at a temperature equal to or more than 95.degree. C. but
equal to or less than 130.degree. C. Since the drying processing is
performed by setting the temperature in the ratio reduction drying
period at a high temperature, and thus convection occurs in the
applied film resin when the hard coat layer is formed, fine surface
roughness is easily produced on the surface of the hard coat layer,
and arithmetic average roughness Ra, which will be described later,
is easily obtained.
[0218] It is known that in general, in a drying process, when the
drying is started, the drying speed is changed from a constant
state to a state where the drying speed is gradually reduced, and a
period in which the drying speed is constant is referred to as a
ratio constant drying period, and a period in which the drying
speed is reduced is referred to as the ratio reduction drying
period. The amount of heat flowing in in the ratio constant drying
period is all consumed for the evaporation of a solvent on the
applied film surface, and when the solvent on the applied film
surface is lowered, the evaporation plane is moved from the surface
thereinto, with the result that the period enters the ratio
reduction drying period. Thereafter, since the temperature of the
applied film surface is increased to approach a hot air
temperature, it can be considered that the temperature of the
ultraviolet-curable resin composition is increased, the viscosity
of the resin is lowered and the fluidity is increased.
[0219] As the light source for the UV curing processing, as long as
a light source that generates ultraviolet rays is used, there is no
restriction. For example, a low pressure mercury lamp, a medium
pressure mercury lamp, a high pressure mercury lamp, an ultra-high
pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a
xenon lamp and the like can be used.
[0220] Although application conditions differ depending on each
lamp, the amount of active rays applied is generally 50 to 1000
mJ/cm.sup.2 and is preferably 50 to 300 mJ/cm.sup.2.
[0221] When active rays are applied, it is preferable to apply
active rays while applying a tension in the transport direction of
the film, and it is further preferable to apply active rays while
also applying a tension in the width direction. The applied tension
is generally 30 to 500 N/m, and is preferably 30 to 300 N/m. A
method of applying a tension is not particularly limited; a tension
may be applied in the transport direction on a back roll or a
tension may be applied either in the width direction at the tenter
or in a biaxial direction. In this way, it is possible to obtain
the film having a more excellent flatness.
[0222] In order to provide an antistatic property, a conductive
agent may be contained in the hard coat layer, and as a preferred
conductive agent, there are metal oxide particles and a
.pi.-conjugated conductive polymer. An ion liquid is preferably
used as a conductive compound.
[0223] A fluorine-siloxane graft polymer or a silicone-based
surfactant may be contained in the hard coat layer.
[0224] The fluorine-siloxane graft polymer refers to a copolymer
that is obtained by grafting, to at least a fluorine-based resin,
polysiloxane and/or organopolysiloxane including siloxane and/or
organosiloxane alone. Examples of the commercially available
product thereof include ZX-022H, ZX-007C, ZX-049, ZX-047-D and the
like made by Fujikasei Kogyo Co., Ltd.
[0225] The silicone-based surfactant is a surfactant that is
obtained by replacing part of a methyl group of silicone oil with a
hydrophilic group. Examples of the hydrophilic group include
polyether, polyglycerin, pyrrolidone, betaine, sulfate, phosphate
and quaternary salt. Specific examples of the product of the
silicone-based surfactant include: SH200, BY16-873 and PRX413
(dimethyl silicone oil; Toray Dow Corning Silicone Co., Ltd.);
SH203, SH230 and SF8416 (alkyl-modified silicone oil; Toray Dow
Corning Silicone Co., Ltd.); SF8417, BY16-208, BY16-209, BY16-849,
BY16-872, FZ-2222 and FZ-2207 (dimethyl polysiloxane.polyethylene
oxide linear block copolymers; FX series made by Nippon Unicar Co.,
Ltd.); KF-101, KF-102 and KF-105 (epoxy-modified silicone oil; made
by Shin-Etsu Chemical Co., Ltd.); and BYK-UV3500, BYK-UV3510,
BYK-333, BYK-331 and BYK-337 (polyether-modified silicone oil; made
by BYK-Chemie Japan Ltd.). However, there is no restriction on
these.
[0226] These components are preferably added to fall within a range
of 0.01 to 5% by mass with respect to the solid component in the
coating liquid.
[0227] (Surface Shape of the Hard Coat Layer)
[0228] The arithmetic average roughness Ra of the surface of the
hard coat layer in the present embodiment is preferably 4 to 20 nm
in terms of an excellent blocking prevention effect at the time of
winding a long film and excellent intimate contact with the
cellulose acetate film. The arithmetic average roughness Ra is a
value that is measured based on the provisions of JIS B0601:1994
with an optical interference type surface roughness meter
(RST/PLUS; made by WYKO Inc.).
[0229] The average distance between the concavo-convex pattern Sm
in the surface of the hard coat layer is preferably 3 to 40 .mu.m.
The ratio (Ra/Sm) of the arithmetic average roughness Ra of the
surface of the hard coat layer to the average distance between the
concavo-convex pattern Sm in the coating surface of the hard coat
layer in the cellulose acetate film (film base member) is
preferably 2.times.10.sup.-4 to 6.times.10.sup.-3. As with the
arithmetic average roughness Ra, it is possible to measure Sm based
on the provisions of JIS B0601:1994 with the optical interference
type surface roughness meter (RST/PLUS; made by WYKO Inc.).
[0230] In order to make the arithmetic average roughness Ra in the
surface of the hard coat layer fall within the above range, it is
possible to use a method of pressing a mold to form projections on
the surface, a method of mixing resins having different SP values
(solubility parameters) to form projections and recesses in the
surface or a method of performing spinodal decomposition,
nucleation or the like to form projections.
[0231] The mold roll used for the formation of the projections can
be selected as necessary from molds ranging from fine projections
and recesses to rough projections and recesses and can be applied;
a mold in which the projections and recesses are regularly aligned
in the form of a mat, a lenticular lens or a sphere or are randomly
aligned can be used.
[0232] The haze value of the hard coat film of the present
embodiment is preferably 1% or less because sufficient brightness
and high contrast can be obtained.
[0233] <Functional Layer>
[0234] (Back Coat Layer)
[0235] On the surface on the opposite side to the side on which the
hard coat layer is provided in the film base member of the present
embodiment, a back coat layer for preventing curl and blocking may
be provided.
[0236] In terms of preventing curl and blocking, the particles of
silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide,
calcium carbonate, talc, clay, calcined kaolin, calcined calcium
silicate, tin oxide, indium oxide, zinc oxide, ITO, hydrated
calcium silicate, aluminum silicate, magnesium silicate and calcium
phosphate can be added.
[0237] The particles included in the back coat layer is 0.1 to 50%
by mass with respect to a binder. The increase in haze when the
back coat layer is provided is preferably 0.5% or less, and is
particularly preferably 0.1% or less. As the binder, a cellulose
ester resin is preferable. A coating composition for the formation
of the back coat layer preferably contains a solvent for alcohols,
ketones and/or acetic acid esters.
[0238] (Anti-Reflection Layer)
[0239] In the upper layer of the hard coat of the present
embodiment, the anti-reflection layer having an external light
anti-reflection function may be provided by coating. The
anti-reflection layer described above corresponds to the
anti-reflection layer 31 in FIG. 1.
[0240] The anti-reflection layer is preferably stacked in layers
with consideration given to refractive index, film thickness, the
number of layers, the order of layers such that the reflectance is
reduced by optical interference. The anti-reflection layer is
preferably formed with a low refractive index layer whose
refractive index is lower than that of the film base member which
is the support member, or by combining a high refractive index
layer whose refractive index is higher than that of the support
member and a low refractive index layer. Particularly preferably,
the anti-reflection layer is formed with three or more refractive
index layers; different three layers, a medium refractive index
layer (whose refractive index is higher than that of the support
member but is lower than that of the high refractive index layer)/a
high refractive index layer/a lower refractive layer, are stacked
in this order from the side of the support member. An
anti-reflection layer is preferably used that has a layer
configuration of four or more layers in which two or more high
refractive index layers and two or more low refractive index layers
are alternately stacked in layers.
[0241] Although as the layer configuration of the film having the
anti-reflection layer, the following configurations can be
considered, there is no restriction on the configurations.
[0242] Cellulose acetate film/hard coat layer/low refractive index
layer
[0243] Cellulose acetate film/hard coat layer/medium refractive
index layer/low refractive index layer
[0244] Cellulose acetate film/hard coat layer/medium refractive
index layer/high refractive index layer/low refractive index
layer
[0245] Cellulose acetate film/hard coat layer/high refractive index
layer (conductive layer)/low refractive index layer Cellulose
acetate film/hard coat layer/anti-glare layer/low refractive index
layer
[0246] (Low Refractive Index Layer)
[0247] The low refractive index layer preferably contains
silica-based particles, and its refractive index preferably falls
within a range of 1.30 to 1.45 when it is measured at 23.degree. C.
with a wavelength of 550 nm.
[0248] The film thickness of the low refractive index layer is
preferably 5 nm to 0.5 .mu.m, is further preferably 10 nm to 0.3
.mu.m and is most preferably 30 nm to 0.2 .mu.m.
[0249] Preferably, a composition for the formation of the low
refractive index layer especially has as silica-based particles, at
least one or more types of particles which have an outer shell
layer and which are porous or have a cavity therewithin. In
particular, the particles which have the outer shell layer and
which are porous or have a cavity therewithin are preferably hollow
silica-based particles.
[0250] The composition for the formation of the low refractive
index layer may also contain an organic silicon compound
represented by the following general formula (OSi-1) or a
hydrolyzate thereof or a polycondensate thereof.
Si(OR).sub.4 General formula (OSi-1):
[0251] In the organic silicon compound represented by the above
general formula, R in the formula represents an alkyl group having
1 to 4 carbon atoms. Specifically, tetramethoxysilane,
tetraethoxysilane, tetraisopropoxysilane or the like is preferably
used.
[0252] In addition, a solvent, as necessary, a silane coupling
agent, a curing agent, a surfactant or the like may be added. A
compound may be contained that has a thermosetting property and/or
a light curing property and that is mainly formed with a
fluorine-containing compound which includes fluorine atoms falling
within a range of 35 to 80% by mass and which includes a
crosslinkable or polymerizable functional group. Specific examples
thereof include a fluorine-containing polymer and a
fluorine-containing sol-gel compound. Examples of the
fluorine-containing polymer include the hydrolyzate and the
dehydration condensate of a perfluoroalkyl group-containing silane
compound [for example,
(heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane] and a
fluorine-containing copolymer that has, constituent units, a
fluorine-containing monomer unit and a cross-linking reactive unit.
In addition, a solvent, as necessary, a silane coupling agent, a
curing agent, a surfactant or the like may be added.
[0253] (High Refractive Index Layer)
[0254] The refractive index of the high refractive index layer is
preferably adjusted to fall within a range of 1.4 to 2.2 when it is
measured at 23.degree. C. with a wavelength of 550 nm. The
thickness of the high refractive index layer is preferably 5 nm to
1 .mu.m, is further preferably 10 nm to 0.2 .mu.m and is most
preferably 30 nm to 0.1 .mu.m. The adjustment of the refractive
index can be performed by adding metal oxide particles or the like.
The refractive index of the metal oxide particles used is
preferably 1.80 to 2.60, and is further preferably 1.85 to
2.50.
[0255] The type of metal oxide particles is not particularly
limited; a metal oxide having at least one type of element selected
from the group consisting of Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd,
As, Cr, Hg, Zn, Al, Mg, Si, P and S. The metal oxide particles may
be doped with a minute number of atom such as Al, In, Sn, Sb, Nb, a
halogen element, Ta or the like. The mixture thereof is also
preferable. In the present embodiment, among them, at least one
type of metal oxide particles selected from the group consisting of
zirconium oxide, antimony oxide, tin oxide, zinc oxide, indium-tin
oxide (ITO), antimony-doped tin oxide (ATO) and zinc antimonate is
particularly preferably used as the main ingredient. In particular,
zinc antimonate particles are preferably contained.
[0256] The average particle diameter of the primary particle of the
metal oxide particles falls within a range of 10 to 200 nm, and
particularly preferably falls within a range of 10 to 150 nm. The
average particle diameter of the metal oxide particles can be
measured with an electron micrograph by a scanning electron
microscope (SEM) or the like. The average particle diameter may
also be measured with a particle size distribution meter or the
like utilizing a dynamic light scattering method, a static light
scattering method or the like. When the particle diameter is
excessively reduced, they are easily flocculated, and the
dispersion property is degraded. When the particle diameter is
excessively increased, it is undesirable because the haze is
remarkable increased. The metal oxide particles are preferably
formed in the shape of a rice grain, a sphere, a cubic, a spindle
or a needle or in an indefinite shape.
[0257] The surface of the metal oxide particles may be processed by
an organic compound. The surface of the metal oxide particles is
modified by an organic compound, and thus the dispersion stability
in an organic solvent is enhanced, the control of the diameter of
the dispersed particles is made easy and it is also possible to
reduce aggregation and sedimentation over time. Hence, the amount
of surface modified by an organic compound is preferably 0.1 to 5%
by mass with respect to the metal oxide particles and is more
preferably 0.5 to 3% by mass. Examples of the organic compound used
for the surface processing include polyol, alkanolamine, stearic
acid, a silane coupling agent and a titanate coupling agent. Among
them, a silane coupling agent is preferable. Two or more types of
surface processing may be combined.
[0258] The high refractive index layer may contain a
.pi.-conjugated conductive polymer. As long as the .pi.-conjugated
conductive polymer is an organic polymer whose main chain is
.pi.-conjugated, it can be used. Examples thereof include
polythiophenes, polypyrroles, polyanilines, polyphenylenes,
polyacetylenes, polyphenylene vinylenes, polyacenes, polythiophene
vinylenes and the copolymers thereof. In terms of ease of
polymerization and stability, polythiophenes, polyanilines and
polyacetylenes are preferable.
[0259] Although it is possible to obtain sufficient conductivity
and solubility in a binder resin even when the .pi.-conjugated
conductive polymer does not undergo substitution, in order to more
enhance the conductivity and the solubility, a functional group
such as an alkyl group, a carboxy group, a sulfo group, an alkoxy
group, a hydroxy group or a cyano group may be introduced.
[0260] The high refractive index layer may also contain an ionic
compound. Examples of the ionic compound include compounds formed
with: imidazolium-based, pyridium-based, alicyclic amine-based,
aliphatic amine-based and aliphatic phosphonium-based cations; and
inorganic ion-based such as BF.sub.4-- and PF.sub.6-- and
fluorine-based such as CF.sub.3SO.sub.2--,
(CF.sub.3SO.sub.2).sub.2N-- and CF.sub.3CO.sub.2-- anions. In the
ratio between the polymer and the binder, the binder is preferably
10 to 400 mass parts with respect to 100 mass parts of the polymer,
and is particularly preferably 100 to 200 mass parts with respect
to the 100 mass parts of the polymer.
[0261] (Anti-Glare Layer)
[0262] On the hard coat layer, an anti-glare layer can be provided
as a functional layer. The anti-glare layer is a layer that blurs
the outline of an image reflected off a film surface to lower the
visibility of the reflected image and that prevents the appearance
of the reflected image from being noticed when an image display
device such as a liquid crystal display, an organic EL display or a
plasma display is used. Specifically, the anti-glare layer is
preferably a layer which is adjusted by the addition of minute
particles or the like to the hard coat layer, a method of pressing
the mold to produce protrusions on the surface or the like such
that the arithmetic average roughness Ra of the layer surface is
0.1 to 1 .mu.m.
[0263] The proportion of a scattering reflectance (scattering
reflectance ratio) in the integrated reflectance of the anti-glare
layer is preferably 2 to 60%. The scattering reflectance ratio
falling within the above range is controlled with minute particles
or the like, and thus it is possible to enhance interlayer intimate
contact between the cellulose acetate film having the degree of
acetylation having high moisture permeability as described above
and the anti-glare layer. More preferably, when the proportion of
the scattering reflectance ratio falls within a range of 20 to 50%,
it is possible to obtain more satisfactory intimate contact.
[0264] The scattering reflectance ratio can be determined by
measuring SCI (integrated reflectance) and SCE (scattering
reflectance) with a spectrophotometer CM-2500d made by Konica
Minolta Inc. under conditions of a measurement diameter of (118 mm
and an observation field of 2.degree..
[0265] [Adhesive Agent Layer]
[0266] The adhesive agent of the adhesive agent layer (which
corresponds to the adhesive agent layer 32 of FIG. 2) used when a
touch panel is adhered to a display device is not particularly
limited, and a known adhesive agent can be used; although for
example, an acrylic-based adhesive agent, a silicone-based adhesive
agent, a urethane-based adhesive agent, a rubber-based adhesive
agent, a polyester-based adhesive agent or the like can be used, an
acrylic-based adhesive agent is particularly preferable because it
is relatively easy to control the adhesive force and the storage
elastic modulus.
[0267] Examples of the acrylic-based adhesive agent include: the
copolymers between one or two or more types of acrylic acid alkyl
esters having 1 to 20 carbon atoms such as methyl (meta) acrylate,
ethyl (meta) acrylate, n-butyl (meta) acrylate, isobutyl (meta)
acrylate, n-hexyl (meta) acrylate, 2-ethylbutyl (meta) acrylate,
2-ethylhexyl (meta) acrylate, isooctyl (meta) acrylate and decyl
(meta) acrylate and functional monomers such as (meta) acrylate,
itaconic acid, maleic acid, maleic anhydride, 2-hydroxyethyl (meta)
acrylate and 4-hydroxybutyl (meta) acrylate copolymerizable with
the acrylic acid alkyl esters are made to react with crosslinking
agents such as an isocyanate-based crosslinking agent, an
epoxy-based crosslinking agent, an aziridine-based crosslinking
agent and a metal chelate-based crosslinking agent.
[0268] The thickness of the adhesive agent layer is preferably 1 to
13 .mu.m. When the thickness of the adhesive agent layer is 1 .mu.m
or more, it is possible to obtain a sufficient adhesive force
whereas when the thickness of the adhesive agent layer is 13 .mu.m
or less, it is possible to reduce the flowing out of glue at the
time of punching processing or at the time of cutting processing,
and to maintain a high pencil hardness. The thickness of the
adhesive agent layer is preferably 3 to 12 .mu.m.
[0269] As the storage elastic modulus of the adhesive agent layer,
a storage elastic modulus at 0.degree. C. is preferably
1.0.times.10.sup.6 to 1.0.times.10.sup.8 Pa. When the storage
elastic modulus of the adhesive agent layer is 1.0.times.10.sup.6
Pa or more, it is possible to obtain sufficient punching processing
and cutting processing properties and a high pencil hardness
whereas when the storage elastic modulus of the adhesive agent
layer is 1.0.times.10.sup.8 Pa or less, it is possible to obtain a
sufficient adhesive force. The storage elastic modulus of the
adhesive agent layer is preferably 1.5.times.10.sup.6 to
1.0.times.10.sup.7 Pa.
[0270] As a method of providing the adhesive agent layer on the
hard coat layer, there is a method of separately coating a
separation sheet with an adhesive agent-containing composition and
stacking in layers, a hard coat film (the film base member+the hard
coat layer) on the adhesive agent layer produced by drying.
Examples of the coating method of the adhesive agent-containing
composition described above include conventional known methods such
as a bar coat method, a knife coat method, a roll coat method, a
blade coat method, a die coat method, a gravure coat method and a
curtain coat method. By directly coating the surface of the hard
coat film with the adhesive agent-containing composition described
above and drying it, the adhesive agent layer may be stacked in
layers.
[0271] As the separation sheet described above, various types of
separation sheets can be used; the separation sheet is typically
formed with a base member sheet having a separation property on the
surface. Examples of the base member sheet include: the films of
polyester resin, polyethylene resin, polypropylene resin,
polystyrene resin, polycarbonate resin and the like; and a film,
synthetic paper and the like in which a filler such as a loading
material is contained in these films. Examples thereof also include
paper base members such as glassine paper, clay coated paper and
high-quality paper.
[0272] In order to have a separation property on the surface of the
base member sheet, it is preferable to adhere, on its surface, such
as by coating, a separation agent such as a heat-curable silicone
resin or an ultraviolet-curable silicone resin. The coating amount
of separation agent is preferably 0.03 to 3.0 g/m.sup.2. The
separation sheet is stacked in layers such that the surface having
the separation agent is in contact with the adhesive agent
layer.
Example
[0273] A specific example of the present invention will be
described below as an example. For comparison with the present
invention, a comparative example will also be described. The
present invention is not limited to the example described
below.
[0274] <Production of an Optical Film A1>
[0275] <Minute Particle Dispersion Liquid 1>
TABLE-US-00001 Silica minute particles (Aerosil R972V made 11 mass
parts by Nippon Aerosil Ltd.) Ethanol 89 mass parts
[0276] They were agitated and mixed with a dissolver for 50
minutes, and were thereafter dispersed with Manton Gaulin, with the
result that a minute particle dispersion liquid 1 was produced.
[0277] <Minute Particle Addition Liquid 1>
[0278] The minute particle dispersion liquid 1 was slowly added,
while being sufficiently agitated, to a dissolution tank filled
with methylene chloride. Furthermore, dispersion was performed with
an attritor such that the particle diameter of the second particle
was a predetermined size. This was filtered with Finemet NF made by
Nippon Seisen Co., Ltd., and a minute particle addition liquid 1
was prepared.
TABLE-US-00002 Methylene chloride 99 mass parts Minute particle
dispersion liquid 1 5 mass parts
[0279] <Main Dope Liquid>
[0280] A main dope liquid of the following composition was
prepared. Methylene chloride and ethanol were first added to a
pressurized dissolution tank. Then, cellulose acetate was put into
the pressurized dissolution tank where a solvent was present while
being agitated. This was heated while being agitated, and was
completely dissolved. This was filtered with Azumi Filter Paper No.
244 made by Azumi Filter Paper Co., Ltd., and the main dope liquid
was prepared.
TABLE-US-00003 Methylene chloride 438 mass parts Ethanol 32 mass
parts Cellulose acetate having an acetyl group substitution 90 mass
parts degree of 2.88 and Mn = 140000 Ester-based compound 1 10 mass
parts TINUVIN 928 (made by Ciba Japan Company Ltd.) 6 mass parts
Minute particle addition liquid 1 4 mass parts
[0281] These were put into a hermetically sealed container, were
heated while being agitated and were completely dissolved. They
were filtered with Azumi Filter Paper No. 24 made by Azumi Filter
Paper Co., Ltd., and the main dope liquid was prepared.
[0282] Then, with a belt cast device, they were uniformly cast to a
stainless band support member. The stainless band support member
was used to evaporate the solvent until the residual solvent amount
reached 100%, and separation from the top of the stainless band
support member was performed. The solvent was evaporated at
35.degree. C. of the web of the cellulose acetate film, slitting
was performed to have a width of 1.5 m, the width was held with a
tenter and drying was performed at a drying temperature (also
referred to a heat processing temperature or an elongation
temperature) of 160.degree. C. The residual solvent amount at the
start of the drying was 20%.
[0283] Thereafter, while the film was being transported with a
large number of rolls within the drying device at 120.degree. C.,
the drying was performed for 15 minutes, and then knurling
processing with a width of 15 mm and a height of 10 .mu.m was
performed on both ends of the film and the film was wound around a
core, with the result that the optical film A1 was obtained. The
residual solvent amount in the optical film was 0.2%, the film
thickness was 25 .mu.m and the number of turns was 3900 m.
[0284] <Production of an Optical Film A2>
[0285] As an optical film A2, KC4UA (made by Konica Minolta
Advanced Layers, Inc., product name: KC4UA, thickness: 40 .mu.m)
was used.
[0286] <Production of an Optical Film A3>
[0287] As an optical film A3, a lactonization polymethyl
methacrylate film having a thickness of 30 .mu.m was used. With
respect to the acrylic-based film described above, a mixture of 90
mass parts of a lactone ring structure-containing (meta)
acrylic-based resin (mass ratio of copolymerization monomer; methyl
methacrylate/2-(hydroxymethyl) methyl acrylic acid=8/2, a lactone
cyclization rate of about 100%) and 10 mass parts of an
acrylonitrile-styrene (AS) resin (Toyo AS AS20 made by Toyo Styrene
Ltd.) was kneaded with a melt extruder, and a transparent pellet
was obtained. The pellet was dissolved in methyl ethyl ketone, and
a solution cast method was used to obtain a lactonization
polymethyl methacrylate film having a thickness of 30 .mu.m. On
both surfaces of the obtained film, an easy adhesive agent
composition shown below was applied such that the thickness after
drying with a bar coater was 0.3 .mu.m, and was thereafter dried at
140.degree. C. to form a specific resin layer, with the result that
the optical film A3 was obtained.
[0288] (Easy Adhesive Agent Composition)
[0289] 16.8 g of polyester urethane (made by Dai-ichi Kogyo Seiyaku
Co., Ltd., product name: Superflex 210, a solid content of 33%),
4.2 g of a crosslinking agent (oxazoline-containing polymer, made
by Nippon Shokubai Co., Ltd., product name: EPOCROS WS-700, a solid
content of 25%), 2.0 g of 1 weight % aqueous ammonia, 0.42 g of
colloidal silica (made by Fuso Chemical Co., Ltd., product name:
Quartron PL-3, a solid content of 20% by weight) and 76.6 g of pure
water were mixed, and thus an easy adhesive agent composition was
obtained.
[0290] <Production of an Optical Film A4>
[0291] As an optical film A4, a polyethylene terephthalate film
(made by Mitsubishi Plastics, Inc., a thickness of 25 .mu.m) was
used.
[0292] <Production of a Hard Coat Film B1>
[0293] A hard coat layer composition below filtered with a
polypropylene filter having a pore diameter of 0.4 .mu.m was
applied on the optical film A1 with an extrusion coater. Then,
after drying at a temperature of 80.degree. C., while nitrogen
purging was being performed such that an atmosphere in which an
oxygen concentration was 1.0% by volume or less was achieved,
ultraviolet rays were applied with an ultraviolet lamp and the
coating layer was cured. The illumination of the ultraviolet rays
at an illumination portion at that time was 100 mW/cm.sup.2, the
amount of illumination was 0.25 J/cm.sup.2. Then, a hard coat layer
having a dry film thickness of 3 .mu.m was formed and wound, and a
hard coat film B1 in the form of a roll was produced.
[0294] <<Hard Coat Layer Composition>>
[0295] The following materials were agitated and mixed to form a
hard coat layer coating composition.
TABLE-US-00004 Dipentaerythritol hexaacrylate 30 mass parts (NK
ester A-DPH made by Shin-Nakamura Chemical Industry Co., Ltd.)
Urethane acrylate 70 mass parts (UA-306H made by Kyoeisha Chemical
Co., Ltd.) Polyether-modified polydimethylsiloxane 1 mass part
(BYK-UV3510 made by BYK-Chemie Japan Ltd.) Irgacure 184 (made by
Ciba Japan Company Ltd.) 4 mass parts Isopropyl alcohol 111 mass
parts Methyl ethyl ketone 74 mass parts
[0296] <Production of Hard Coat Films B2 to B5>
[0297] Instead of the optical film A1, the optical films A2 to A4
were used, and hard coat films B2 to B4 were obtained in the same
production manner as the hard coat film B1. The hard coat film B3
was immersed in pure water for 60 seconds, was then dried in an
oven at 60.degree. C. for 60 seconds and thus the hard coat film B5
was obtained.
[0298] The relationship between the hard coat films B1 to B5, the
optical films A1 to A4 used, the materials thereof and the film
thickness (including the thickness of the optical films A1 to A4)
of the hard coat films B1 to B5 is shown in table 1.
TABLE-US-00005 TABLE 1 Film base HC film HC film member HC layer
thickness (.mu.m) B1 A1 (TAC) HC layer 28 B2 A2 (TAC) composition
43 B3 A3 (Acryl) 33 B4 A4 (PET) 28 B5 A3 (Acryl) 33 (obtained by
washing B3)
[0299] [Production of a Polarization Plate]
[0300] The hard coat film B1 produced as described above was
alkali-processed with 2.5 mol/L of a sodium hydroxide aqueous
solution at 40.degree. C. for 90 seconds, was washed with water for
45 seconds, was neutralized with 10 mass % of HCl at 30.degree. C.
for 45 seconds, was then washed at 30.degree. C. for 45 seconds and
was subjected to saponification processing, with the result that an
alkali-processed film was obtained.
[0301] Then, a polyvinyl alcohol film having a thickness of 75
.mu.m was swollen with water at 35.degree. C. This film was
immersed in an aqueous solution consisting of 0.075 g of iodine, 5
g of potassium iodide and 100 g of water for 60 seconds, and was
then immersed in an aqueous solution consisting of 3 g of potassium
iodide, 7.5 g of boric acid and 100 g of water at 45.degree. C. The
film after the immersion was uniaxially stretched at 55.degree. C.
by a stretching factor of 5. The obtained film was washed with
water and was then dried, and thus a polarizer having a thickness
of 35 .mu.m was obtained.
[0302] Then, a polarization plate C1 was produced by adhering the
alkali-processed film to the polarizer using a completely
saponified polyvinyl alcohol 5% aqueous solution as an adhesive
agent such that the hard coat layer formed a front layer on one
surface of the polarizer and adhering, to the other surface, a film
obtained by likewise alkali-processing the optical film A1.
[0303] In the same manner as described above, polarization plates
C2 and C6 were produced with combinations shown in table 2.
Polarization plates C3 to C5 and C7 were produced using adhering
methods shown below.
TABLE-US-00006 TABLE 2 Display Display HC film HC film unevenness
unevenness Display Polarization Adhering Polarizer Polarizer
thickness contact 23.degree. C. 50.degree. C. device plate method
front side back side (.mu.m) angle (.degree.) 55% RH 90% RH Example
1 D1 C1 Water glue B1 A1 28 55.degree. Excellent Excellent
Comparative D2 C2 Water glue B2 A1 43 55.degree. Excellent No good
example 1 Comparative D3 C3 UV B3 A1 33 80.degree. Fair No good
example 2 adhesive Comparative D4 C4 UV B4 A1 28 80.degree. Fair No
good example 3 adhesive Comparative D5 C5 UV B1 A1 28 80.degree.
Fair No good example 4 adhesive Example 2 D6 C6 Water glue A1 A1 25
20.degree. Excellent Fair Example 3 D7 C7 UV B5 A1 33 55.degree.
Excellent Fair adhesive
[0304] An adhesion layer composition shown below was applied to
each of the optical film A1 and the hard coat films B1 and B3 to B5
with a micro gravure coater (gravure roll: #300, rotation speed
140%/line speed) such that the thickness after curing was 5 .mu.m,
and thus a protective film with the adhesive agent was
obtained.
[0305] The protective film with the adhesive agent was adhered to
both surfaces of the polarizer described above with the
combinations shown in table 2 with a roll machine. Thereafter,
ultraviolet rays were applied from both sides to cure the adhesive
agent. The line speed was set at 20 m/min, and the cumulative
amount of ultraviolet rays applied to the protective film was each
set at 200 mJ/cm.sup.2. In this way, the polarization plates C3 to
C5 and C7 were obtained.
[0306] [Production of a Display Device with a Touch Panel (without
any Air Gap)]
[0307] From a commercially available liquid crystal display device
with a touch panel (GALAXY S III, made by Samsung Co., Ltd.), a
touch panel module and a polarization plate adhered to a liquid
crystal cell (liquid crystal panel) on the side of the touch panel
module were carefully separated.
[0308] Then, the liquid crystal cell was adhered through an
acryl-based adhesive agent to the polarization plate C1 produced as
described above, and thus a liquid crystal display device was
produced.
[0309] SVR1240 made by Sony Chemical & Information Device Corp.
was applied to the surface of the hard coat film B1 of the liquid
crystal display device produced as described above, and thus an
adhesive agent layer was formed.
[0310] Then, through the applied SVR1240, the liquid crystal
display device produced as described above and the touch panel were
adhered, ultraviolet rays were applied to part thereof and they
were tentatively fixed. Whether or not bubbles were produced at the
interface was inspected, then ultraviolet rays were applied
overall, curing was completely performed and the liquid crystal
display device and the touch panel were actually fixed, with the
result that the display device with the touch panel D1 was
obtained.
[0311] In the same manner as described above, an adhesive agent
layer was formed on the polarization plates C2 to C7 of the liquid
crystal display device, and the touch panel and the liquid crystal
display device were adhered through the adhesive agent layer, with
the result that the display devices with the touch panel D2 to D7
were obtained.
[0312] [Production of a Display Device with a Touch Panel (with Air
Gaps)]
[0313] <<Low Refractive Index Layer Composition>>
[0314] A fluorine polymer (molecular weight 1000000), 80 parts by
weight of low refractive index nano-particles with respect to 100
parts by weight of the fluorine polymer, 40 parts by weight of an
acryl monomer (molecular weight 1000) with respect to 100 parts by
weight of the fluorine polymer, 1 part by weight of a
fluorine-based additive with respect to 100 parts by weight of the
fluorine polymer and 1 part by weight of a silicone-based additive
with respect to 100 parts by weight of the fluorine polymer were
combined to prepare a liquid, and MIBK (methyl isobutyl
ketone):t-BuOH (t-butyl alcohol):cyclohexanone=20:55:25 was added,
with the result that a 3.5 wt % low refractive index layer
composition was produced.
[0315] (Production of Anti-Reflection Films)
[0316] On the hard coat films B1 to B5 described above, the low
refractive index layer composition produced as described above was
applied, and was dried at an oven at 80.degree. C. for 40 seconds
such that the film thickness was 100 nm. After the drying, an
ultraviolet application device (Fusion UV Systems Japan, light
source H valve) was used under nitrogen purging, and ultraviolet
rays were applied at an application dose of 380 mJ/m.sup.2, the low
refractive index layer composition was cured and a low refractive
index layer was produced, with the result that anti-reflection
films (LR (Low Reflection) film) E1 to E5 were produced.
[0317] A relationship between the anti-reflection films E1 to E5,
the hard coat films B1 to B5 used and the film thickness thereof is
shown in table 3.
TABLE-US-00007 TABLE 3 HC film thickness LR film HC film Low
refractive index layer (.mu.m) E1 B1 Low refractive index layer 28
E2 B2 composition 43 E3 B3 33 E4 B4 28 E5 B5 33
[0318] (Production of Polarization Plates)
[0319] As with the polarization plates C1 to C7, the polarizer
having a thickness of 35 .mu.m and produced under the same
conditions as described previously was used to adhere the
anti-reflection films E1 to E5 to the polarizer with combinations
shown in table 4, with the result that polarization plates C8 to
C13 were produced.
TABLE-US-00008 TABLE 4 Display Display HC film HC film unevenness
unevenness Display Polarization Adhering Polarizer Polarizer
thickness contact 23.degree. C. 50.degree. C. device plate method
front side back side (.mu.m) angle (.degree.) 55% RH 90% RH Example
4 D8 C8 Water glue E1 A1 28 55.degree. Excellent Excellent
Comparative D9 C9 Water glue E2 A1 43 55.degree. Excellent No good
example 5 Comparative D10 C10 UV E3 A1 33 80.degree. Fair No good
example 6 adhesive Comparative D11 C11 UV E4 A1 28 80.degree. Fair
No good example 7 adhesive Comparative D12 C12 UV E1 A1 28
80.degree. Fair No good example 8 adhesive Example 5 D13 C13 UV E5
A1 33 55.degree. Excellent Fair adhesive
[0320] (Adherence)
[0321] From a commercially available liquid crystal display device
with a touch panel (iPad II, made by Apple, Ltd.), a touch panel
module and a polarization plate adhered to a liquid crystal cell
were carefully separated.
[0322] Then, the liquid crystal cell was adhered through an
acryl-based adhesive agent to the polarization plates C8 to C13
produced as described above, and thus a liquid crystal display
device was produced.
[0323] Then, an optical adhesive tape (having a thickness of 0.025
mm, made by Nitto
[0324] Denko Co., Ltd.) was adhered to the edge portion of the
liquid crystal display device described above, and the liquid
crystal display device and the touch panel were adhered, with the
result that the display devices with the touch panel D8 to D13 were
obtained.
[0325] [Measurement of a Contact Angle]
[0326] In samples obtained by performing wet heat processing at a
temperature of 23.degree. C. and 55% RH (relative humidity) for 24
hours on each of the hard coat films produced as described above, a
contact angle on the surface (the surface on the side of the touch
panel) of each film was measured with a contact angle meter CA-A
(made by Kyowa Interface Science Co., Ltd.). In the measurement of
the contact angle, pure water was used, and the droplet diameter
was set at 1.0 mm under the temperature and humidity described
above, and the contact angle was measured.
[0327] 20 samples with a size of 30 mm.times.40 mm were randomly
sampled from the individual films produced, and on the surface of
each sample, the contact angle was measured by the method described
above, with the result that the average value of the measurements
of 20 samples of the individual films was adopted.
[0328] [Measurement of Display Unevenness]
[0329] Wet heat processing was performed on each of the display
devices D1 to D13 produced as described under the environment of
23.degree. C. and 55% RH for 24 hours. Thereafter, a backlight was
turned on for 2 hours, and then the maximum brightness and the
minimum brightness at the time of black display were measured with
a brightness distribution measurement device (manufactured by
Konica Minolta Inc, product name "CA-1500").
[0330] The maximum brightness and the minimum brightness were
measured as follows. Specifically, the display screen of the liquid
crystal display device was divided into a total of 9 partitions of
3 partitions horizontally.times.3 partitions vertically. Then, the
brightness in the partition in the center was set at the minimum
brightness, and the highest brightness among the total partitions
(9 partitions) was set at the maximum brightness. The obtained
maximum brightness was divided by the minimum brightness, and thus
a black brightness ratio was calculated (black brightness
ratio=maximum brightness/minimum brightness). Then, display
unevenness was evaluated based on the following criteria.
[0331] Excellent: the black brightness ratio was less than 1.50
[0332] Fair: the black brightness ratio was equal to or more than
1.50 but is less than 2.00
[0333] No good: the black brightness ratio was equal to or more
than 2.00
[0334] Wet heat processing was performed on the obtained display
devices D1 to D13 under the environment of 50.degree. C. and 90% RH
for 24 hours. Thereafter, the black brightness ratio was measured
in the same manner as described above, and display unevenness was
evaluated.
[0335] A correlation between the display devices D1 to D13 and
examples (or comparative examples) is shown as in tables 2 and
4.
[0336] [Evaluation Results]
[0337] With respect to the display devices D1, D6 to D8 and D13,
the contact angle on the surface of the hard coat film was
60.degree. or less, and since the adhesion of the anti-reflection
film or the adhesive agent layer to the film surface was enhanced,
all evaluations of the display unevenness after the wet heat
processing under the environment of 23.degree. C. and 55% RH were
excellent. Since in these display devices, the evaluations of the
display unevenness after the wet heat processing under the
environment of 50.degree. C. and 90% RH were either excellent or
fair, the film thickness of the hard coat film was so thin as to be
35 .mu.m and thus the warpage of the film after heating was
reduced, with the result that it is estimated that this further
reduced the separation of the anti-reflection film and the adhesive
agent layer.
[0338] On the other hand, since in the other display devices D2 to
D5 and D9 to D12, at least one of the conditions "the film
thickness of the hard coat film was equal to or less than 35 .mu.m"
and "the contact angle on the surface of the hard coat film was
less than 60.degree." was not satisfied, the evaluations of the
display unevenness included no good.
[0339] Hence, it can be said that the film thickness of the hard
coat film was equal to or less than 35 .mu.m and the contact angle
on the surface was less than 60.degree., and thus the adhesion of
the anti-reflection film or the adhesive agent layer to the hard
coat film was enhanced, and it was possible to reduce display
unevenness caused by the separation thereof, with the result that
it was possible to prevent the decrease in the visibility of the
display device. In particular, the film thickness of the hard coat
film was equal to or less than 35 .mu.m and thus it is possible to
sufficiently reduce the thickness of the polarization plate, with
the result that it is possible to sufficiently contribute to the
reduction in the thickness of the display device and the reduction
in the weight thereof.
[0340] Since with respect to the evaluations of the display
unevenness after the wet heat processing under the environment of
50.degree. C. and 90% RH, when the film thickness of the hard coat
film was 33 .mu.m and the contact angle on the surface was
55.degree., the evaluations were either excellent or fair whereas
when the film thickness of the hard coat film was 43 .mu.m and the
contact angle on the surface was 80.degree., the evaluations were
no good, it can be considered that the upper limit of the film
thickness of the hard coat film was 35 .mu.m, which was between 33
.mu.m and 43 .mu.m and was close to 33 .mu.m, and it can be
considered that the upper limit of the contact angle was
60.degree., which was between 55.degree. and 80.degree. and was
close to 60.degree.. It can be said from tables 2 and 4 that in
order to reduce display unevenness, the film thickness of the hard
coat film is preferably equal to or less than 33 .mu.m and is more
preferably equal to or less than 28 .mu.m, and that the contact
angle on the surface of the hard coat film is preferably equal to
or less than 55.degree..
INDUSTRIAL APPLICABILITY
[0341] The present invention can be utilized when a touch panel is
fitted through an anti-reflection layer or an adhesive agent layer
to the front surface of a liquid crystal display device or an
organic EL television set.
LIST OF REFERENCE SYMBOLS
[0342] 1 display panel [0343] 2 polarization plate [0344] 3
polarizer [0345] 4 film [0346] 10 display device [0347] 20 touch
panel [0348] 31 anti-reflection layer [0349] 32 adhesive agent
layer
* * * * *